https://novaprd-lb.newcastle.edu.au/vital/access/manager/Index ${session.getAttribute("locale")} 5 Central opiate system regulation of baroreflex control of coronary conductance https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12908 Wed 28 Oct 2020 09:44:30 AEDT ]]> Exercise and the heart in hypertension https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12714 Wed 28 Oct 2020 09:42:57 AEDT ]]> Coronary haemodynamics in unrestrained conscious baboons https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12681 Wed 28 Oct 2020 09:39:58 AEDT ]]> The role of central catecholamines in the control of blood pressure through baroreceptor reflex and nasopharyngeal reflex in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12716 Wed 24 Jul 2013 22:25:37 AEST ]]> Central integration of cardiopulmonary autonomic controls https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12889 Wed 24 Jul 2013 22:25:22 AEST ]]> Effects of central nervous opoid and 5-hydroxytrptamine interactions on coronary conductance regulation in the conscious dog https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12724 Wed 24 Jul 2013 22:25:20 AEST ]]> Accuracy of continuous non-invasive impedance cardiographic measurements of stroke volume in exercising man https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12691 2 rebreathing method, however, still suffers from relatively poor accuracy at rest, and gated pool radionuclide scanning requires high levels of medical technological expertise under confined laboratory conditions. Impedance cardiography (IC) does not suffer from these disadvantages. We have evaluated the accuracy of impedance cardiography against accepted invasive methods e.g. thermodilution (TD), dye dilution (DD), the electromagnetic flowmeter (EM), in models where different degrees of experimental control could be applied. This approach was necessary due to the empirical aspects of the Kubicek formula for the calculation of stroke volume using IC. In addition, we have assessed the accuracy of the independent methods in clinical usage, as the assessment of accuracy of impedance cardiography would depend to some extent on the accuracy of the independent method used. Using regression analysis of simultaneous estimates of SV and CO, the accuracy of TD (against EM) in rabbits is 1.0% (S.E. of a single CO estimate expressed as % of mean CO (492 ± 3.5 ml), and that of IC SV measurements in the dog (against EM) is 1.7% (22.2 ± 0.4ml). In man, the accuracy of right heart thermodilution SV measurements (against DD) is 3.9% (75.4 3.0ml), and that for IC SV measurements (against TD) is 2.1 % (58.2 ± 1.2ml). These results indicate that both the invasive TD, and the non-invasive IC systems used in our laboratories have comparable and satisfactory accuracies for SV measurement, and suggest that under conditions of normal hearts and lungs, IC is useful for accurate and continuous non-invasive stroke volume measurements in exercising man, provided certain conditions of usage are satisfied.]]> Wed 24 Jul 2013 22:25:16 AEST ]]> Simulation of arterial chemoreceptor control of ventilation but not of arterial pressure by intracisternal infusion of substance P https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12694 Wed 24 Jul 2013 22:25:15 AEST ]]> Calibration of the ultrasonic Doppler flowmeter in situ https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12695 Wed 24 Jul 2013 22:25:15 AEST ]]> Nasopharyngeal reflexes: role of brain monoamines in central integration: a review https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12711 Wed 24 Jul 2013 22:24:45 AEST ]]> Cardioselective inhibition of sympathetic control by atenolol in man does not evoke fatigue: a double-blind study https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12753 Wed 24 Jul 2013 22:24:43 AEST ]]> Central nervous μ-opioid and 5-hydroxytryptamine influence on baroreflex evoked coronary vasodilatation in the dog https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12746 Wed 24 Jul 2013 22:24:31 AEST ]]> Factors regulating coronary blood flow in the normal and diseased heart https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12705 2) appears to be the major determinant of CBF and the factors determining MVo2 (mainly developed tension and contractile state) are, therefore, major determinants of CBF. The direct effects of autonomic excitation on CBF appear relatively minor, however; the vagus, sympathetic nerves and adrenal medullary hormones profoundly alter CBF indirectly through changes in MVo2. In the eschaemic heart with atheromatous occlusion of large vessels there is a reduced capacity for autoregulation, and nutrient flow is more dependent on pressure gradient. Hypertension and valvular disorders are often associated with raised MVo2 but associated abnormalities in pressure gradient and resistance to flow often hinder the supply of CBF needed to meet high demands.]]> Wed 24 Jul 2013 22:24:23 AEST ]]> Drug controversy in sport : the socio-ethical and medical issues https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12677 Wed 24 Jul 2013 22:23:50 AEST ]]> Teenage ballet dancers as a model of the female athlete: sensitivity of endocrine control in the menstrual cycle to exercise https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12678 Wed 24 Jul 2013 22:23:50 AEST ]]> A comparison between thermodilution, electromagnetic and Doppler methods for cardiac output measurement in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12680 Wed 24 Jul 2013 22:23:50 AEST ]]> The role of cardiac vagal afferents and arterial baroreceptors in the circulatory adjustments to hemorrhage in the cat https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12666 Wed 24 Jul 2013 22:23:44 AEST ]]> Neurogenic control of the coronary circulation https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12656 Wed 24 Jul 2013 22:23:43 AEST ]]> Coronary haemodynamic effect of nifedipine (Bay a 1040) and glyceryl trinitrate in unanaesthetized dogs https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12657 Wed 24 Jul 2013 22:23:43 AEST ]]> Circulatory responses to interruption of and stimulation of cardiac vagal afferents https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12663 Wed 24 Jul 2013 22:23:43 AEST ]]> Sex differences in substrate utilisation during prolonged submaximal exercise https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12672 2 max. Each subject worked for 2 hours on a cycle ergometer at 50% of individual V02 max. There were thus no significant between-group differences in relative workload, but the trained subjects (groups 1, 2 and 4) worked at significantly higher absolute workload than the untrained subjects (groups 3 and 5) in order to achieve the same work level relative to their 'fitness'. Regression analysis of R on time for the different groups revealed the following: 1) at the onset of exercise females utilise a greater proportion of fat than males; 2) except in elite male athletes, training, in both sexes, tends to alter the energy substrate utilisation at the onset of exercise, in favour of greater fat metabolism; 3) during endurance exercise in all groups, the proportion of fat utilised increases significantly with time; 4) elite male athletes appear to be different in the sense that they utilise less fat at the onset of exercise than lesser trained subjects; however during endurance performance their substrate usage changes at a greater rate resulting in the utilisation of the same (or greater) proportion of fat as observed in the lesser trained subjects. It has been proposed that the capacity to utilise more fat in endurance performance may be a function of the carbohydrate sparing effects of female sex-hormones on intermediary metabolism. We have found high oestradiol levels in highly trained males (Brown, et al., 1980. Proc. Aust. Physiol. Pharmacol. Soc. 11, 131), and it is suggested that all highly trained athletes 'reset' their hormonal systems to facilitate the utilisation of fat as an energy source during endurance performance. 'Hitting the wall' in males, therefore, may be a mismatch between the induction of rapid carbohydrate utilisation at the beginning of exercise, and the facilitation of fat utilisation which may be dependent on high circulation levels of sex hormones, of which oestradial could play a highly significant role.]]> Wed 24 Jul 2013 22:23:42 AEST ]]> The peripheral vascular response to severe exercise in untethered dogs before and after complete heart block https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12673 Wed 11 Apr 2018 16:58:10 AEST ]]> The new science of exercise: the invited lecture https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12688 Wed 11 Apr 2018 09:50:38 AEST ]]> Control of the thoracic circulations https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12757 Wed 11 Apr 2018 09:18:59 AEST ]]> Hemodynamic response to exercise for prediction of development of kidney failure revealing a cardiorenal secret cross talk https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:30003 Thu 13 Jan 2022 10:28:39 AEDT ]]> The price athletes pay in pursuit of Olympic gold https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12707 Thu 03 Sep 2020 09:59:00 AEST ]]> Central nervous integration of coronary reflexes https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12744 Thu 03 Sep 2020 09:11:32 AEST ]]> Learning for change in medical practice: proceedings of the annual forum, the Australian Postgraduate Federation in Medicine, Newcastle N.S.W, 12th-13th May 1987 https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12720 Thu 03 Sep 2020 09:11:30 AEST ]]> Modification of body temperature regulation in surgical patients https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12659 Thu 03 Sep 2020 09:11:29 AEST ]]> Coronary-bronchial blood flow and airway dimensions in exercise-induced syndromes https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:1971 Sat 24 Mar 2018 08:33:15 AEDT ]]> Effect of fentanyl on baroreflex control of circumflex coronary conductance https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:2925 Sat 24 Mar 2018 08:32:18 AEDT ]]> Effects of anaesthesia on regional coronary control mechanisms https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:2994 Sat 24 Mar 2018 08:30:22 AEDT ]]> Venous hydrostatic indifference point as a marker of postnatal adaptation to orthostasis in swine https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:2825 Sat 24 Mar 2018 08:28:25 AEDT ]]> Analysis of bronchovascular downstream blood pressure changes in exercising sheep https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:1393 Sat 24 Mar 2018 08:28:02 AEDT ]]> Neural control of the bronchial circulation https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:1396 Sat 24 Mar 2018 08:28:01 AEDT ]]> Long-term measurement of bronchial vascular resistance in awake sheep and dogs https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:1392 Sat 24 Mar 2018 08:27:59 AEDT ]]> Effects of hyperventilation on the circulatory response of the rabbit to arterial hypoxia https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12732 Sat 24 Mar 2018 08:18:43 AEDT ]]> The effects of chloralose urethane and sodium pentobarbitone anaesthesia on the local and autonomic components of the circulatory response to arterial hypoxia. https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12725 Sat 24 Mar 2018 08:18:26 AEDT ]]> Central nervous system 5-hydroxytryptamine and noradrenaline specificity of ear vascular and ventilation reflexes in thermoregulating rabbits https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12701 Sat 24 Mar 2018 08:18:25 AEDT ]]> The role of substance P in arterial chemoreflex control of ventilation https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12699 Sat 24 Mar 2018 08:18:25 AEDT ]]> Central integration of the autonomic cardiorespiratory response to nasopharyngeal stimulation in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12703 Sat 24 Mar 2018 08:18:25 AEDT ]]> Circulatory effects of chloralose urethane and sodium pentobarbitone anaesthesia in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12722 Sat 24 Mar 2018 08:18:25 AEDT ]]> Central nervous system opiate and 5-hydroxytryptamine influences on baroreflex control of the coronary circulation https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12702 Sat 24 Mar 2018 08:18:24 AEDT ]]> Role of central nervous system monoamines in cardiopulmonary effects of Althesin in rabbit and man https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12700 Sat 24 Mar 2018 08:18:24 AEDT ]]> Impedance cardiography for cardiac output measurement: An evaluation of accuracy and limitations https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12763 Sat 24 Mar 2018 08:18:18 AEDT ]]> Dynamic range of evoked cholinergic and non-cholinergic non-adrenergic vasodilatation in bronchoesphageal circulation in the awake dog https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12782 Sat 24 Mar 2018 08:17:34 AEDT ]]> Modulation of baroreflex gain regulating coronary vasodilator responses by the central μ-opioid receptor agonist fentanyl https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12783 Sat 24 Mar 2018 08:17:34 AEDT ]]> Coronary blood flow regulation in health and disease https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12784 Sat 24 Mar 2018 08:17:34 AEDT ]]> Autonomic control of bronchial circulation in awake sheep during rest and behaviour https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12828 G-nitro-L-arginine following blockade of α- and β-adrenoceptors and cholinoceptors causes hypertension, but minor changes, if any, in pulmonary pressures or heart rate. Bronchial flow and conductance, however, fall from a higher resting conductance by approximately 50%, suggesting that, normally, resting bronchial flow conductance is dominated by strong tonic NO vasodilator effects that interact with weaker tonic autonomic vasoconstrictor effects.6. Superimposed (respiratory) behaviours of sighing, sneezing and coughing, which involve negative swings in intrathoracic pressure and the movement of inspired air, evoke large active bronchovascular dilator effects. These appear to be largely NANC in origin and appear to be dependent, in part, on mechanisms associated with NO release. It is postulated that the C-fibre axon reflex using substance P, calcitonin gene-related peptide and neurokinin A may be involved. Vocalization and eructation do not evoke bronchovascular effects.]]> Sat 24 Mar 2018 08:17:16 AEDT ]]> Role of central 5-hydroxytryptamine nerves in tonic, thermal and arterial chemoreflex control of ear vessel sympathetic innervation https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12890 Sat 24 Mar 2018 08:17:13 AEDT ]]> Does my middle aged male patient have coronary artery disease underlying his vague chest discomfort? https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12891 Sat 24 Mar 2018 08:17:13 AEDT ]]> Impedance cardiography: clinical limitations and accuracy https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12892 Sat 24 Mar 2018 08:17:13 AEDT ]]> The effects of haemorrhage in the unanaesthetized rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12689 Sat 24 Mar 2018 08:16:55 AEDT ]]> The relative roles of the aortic and carotid sinus nerves in the rabbit in the control of respiration and circulation during arterial hypoxia and hypercapnia https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12687 Sat 24 Mar 2018 08:16:55 AEDT ]]> Nasopharyngeal reflexes: integrative analysis of evoked respiratory and cardiovascular effects https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12693 Sat 24 Mar 2018 08:16:54 AEDT ]]> Some mechanisms of reflex control of the circulation by the sympatho-adrenal system https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12690 Sat 24 Mar 2018 08:16:54 AEDT ]]> Role of the autonomic nervous system in the renal vasoconstriction response to hemorrhage in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12692 Sat 24 Mar 2018 08:16:53 AEDT ]]> Circulatory effects mediated through cardiac vagal afferents https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12735 Sat 24 Mar 2018 08:16:52 AEDT ]]> Central nervous integration of the circulatory and respiratory responses to arterial hypoxemia in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12734 Sat 24 Mar 2018 08:16:51 AEDT ]]> Metabolic patterns in endurance exercise: a role for the sex hormones? https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12745 Sat 24 Mar 2018 08:16:37 AEDT ]]> Dynamic control of the bronchial circulation in the conscious dog: preliminary data on the role of alpha and beta adrenoceptors, and of cholinoceptors https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12747 Sat 24 Mar 2018 08:16:36 AEDT ]]> A comparison of blood viscosity measured in vitro and in a vascular bed https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12743 Sat 24 Mar 2018 08:16:36 AEDT ]]> Suprabulbar and bulbar integration of ventilation and ear vascular control during thermoregulation in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12710 A) was maintained sequentially at 22°C, 12°C, 22°C and 35°C, with an accuracy of ±1°C. Neither thalamic nor pontine rabbits could maintain core temperature in cold or heat. At T 35°C, thalamic and pontine animals did not pant, indicating that telencephalic responses were necessary for the integration of mechanisms promoting respiratory heat loss. Thalamic animals, however, could inhibit ear vascular sympathetic tone in the heat, but the response was absent in pontine animals, suggesting diencephalic responses were essential for the integration of mechanisms promoting ear skin heat loss. Thus, the neural adjustments to thermal stress depend on mechanisms of integration distributed longitudinally throughout the central nervous sytem, and different components of the reflex cardiorespiratory response depend on different sites in the central nervous system for their full expression.]]> Sat 24 Mar 2018 08:16:20 AEDT ]]> Baroreflex control of coronary conductance in normotensive and renal hypertensive dogs with complete heart block https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12715 Sat 24 Mar 2018 08:16:19 AEDT ]]> Evaluation of the Doppler flowmeter for measurement of blood flow in small vessels of unanaesthetized animals https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12713 Sat 24 Mar 2018 08:16:19 AEDT ]]> Haemodynamic effects of arrhythmias : effects of alterations in ventricular rate on cardiac output and peripheral flow distribution https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12712 Sat 24 Mar 2018 08:16:19 AEDT ]]> Adrenalectomy in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12655 Sat 24 Mar 2018 08:15:50 AEDT ]]> Evaluation of blood resistivity in vivo for impedance cardiography in man, dog and rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12668 z) has been controversial. This could be, in part, due to the use in the Kubicek formula of the bench-determined blood resistivity (p)-haematocrit (Hct) relationship, which does not take into account factors such as complex blood-velocity movements. In the present study in vivo, p was calculated in dog, rabbit and man from the rearranged Kubicek formula, p = (SV. Zo2)/(L2. dZ/dt max T); the stroke volumes used in the calculation being derived at different Hcts in the different species from the independent techniques of electromagnetic flowmeter, direct Fick, and direct Fick and thermodilution, respectively. The in vivo p-Hct relationship is linear, inverse and nearly constant over the range of Hcts tested (dog 26–62%, man 31–48%, rabbit 37%). No significant difference exists between meanin vivo p values determined for the three species at corresponding haematocrits despite different thoracic anatomy and circulatory dynamics. Thus, the best estimate of mean p in vivo within the normal Hct range is 135Ωcm, the use of which will result in a SVz accuracy of better than ± 10%.]]> Sat 24 Mar 2018 08:15:49 AEDT ]]> Autonomic cardiovascular effects of nasal inhalation of cigarette smoke in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12665 diff< 0001). The circulatory changes thus appear to conserve body oxygen stores during the induced apnoea, an effect dependent on the integration of evoked vagal and sympathetic autonomic activity.]]> Sat 24 Mar 2018 08:15:49 AEDT ]]> Local and reflex factors affecting the distribution of the peripheral blood flow during arterial hypoxia in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12669 b) and Lₐ. After habituation for 7 days to 29°C and 12:12-h dark-light cycles, 48 h of baseline data were acquired from six control and four experimental rats. The mean Tb for the group oscillated from a nocturnal peak of 38.4 ± 0.18°C (SD) to a diurnal nadir of 36.7 ± 0.15°C. Then the experimental group was switched to 10% O₂ in N₂. The immediate Tb response, phase I, was a disappearance of circadian rhythm and a fall in Tb to 36.3 ± 0.52°C. In phase II, Tb increased to a peak of 38.7 ± 0.64°C. In phase III, Tb gradually decreased. At reoxygenation at the end of the hypoxic period, phase IV, Tb increased 1.1 ± 0.25°C. Before hypoxia, Lₐ decreased 70% from its nocturnal peak to its diurnal nadir and was entrained with Tb. With hypoxia Lₐ decreased in phase I to essential quiescence by phase II. Lₐ had returned, but only to a low level in phase III, and was devoid of any circadian rhythm. Lₐ resumed its circadian rhythm on reoxygenation. We conclude that 63 h of sustained hypoxia 1) completely disrupts the circadian rhythms of both Tb and Lₐ throughout the hypoxic exposure, 2) the hypoxia-induced changes in Tb and Lₐ are independent of each other and of the circadian clock, and 3) the Tb response to hypoxia at thermoneutrality has several phases and includes both hypothermic and hyperthermic components.]]> Sat 24 Mar 2018 08:15:49 AEDT ]]> Local thermodilution method for measuring blood flow in the portal and renal veins of the unanaesthetized rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12667 Sat 24 Mar 2018 08:15:49 AEDT ]]> The control of the circulation in skeletal muscle during arterial hypoxia in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12662 35 mm Hg) in the rabbit, muscle blood flow did not change, although cardiac output increased. During moderate hypoxia (Po₂ 30 - 35 mm Hg) there was initial vasoconstriction in muscle, followed by a return to control values paralleling the changes in cardiac output. In severe arterial hypoxia (Po₂ < 30 mm Hg) the initial vasoconstriction was less marked, and during the 'steady state' there was a large vasodilatation and increase in muscle blood flow, at a time when the cardiac output was not elevated. 3. The early vasoconstriction in arterial hypoxia is mediated mainly through sympathetic vasoconstrictor nerves as a result of strong arterial chemoreceptor stimulation. 4. Increased secretion of adrenaline is an important factor in restoring muscle blood flow to control values during moderate arterial hypoxia, and in elevating the muscle blood flow above these values in severe hypoxia. The peripheral dilator (β-)effects of adrenaline oppose the peripheral constrictor (α-) effects resulting from increased activation of sympathetic constrictor nerves during arterial hypoxia.]]> Sat 24 Mar 2018 08:15:49 AEDT ]]> Role of trigeminal, olfactory, carotid sinus and aortic nerves in the respiratory and circulatory response to nasal inhalation of cigarette smoke and other irritants in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12660 Sat 24 Mar 2018 08:15:48 AEDT ]]> Circulatory control in hypoxia by the sympathetic nerves and adrenal medulla https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12658 Sat 24 Mar 2018 08:15:48 AEDT ]]> Distribution of peripheral blood flow in primary tissue hypoxia induced by inhalation of carbon monoxide https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12675 Sat 24 Mar 2018 08:15:41 AEDT ]]> Effects of haemorrhage on the distribution of the peripheral blood flow in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12679 Sat 24 Mar 2018 08:15:41 AEDT ]]> The hypothetical : drugs in sport : "the birth of superman" https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12719 Sat 24 Mar 2018 08:15:19 AEDT ]]> Patterns of physical conditioning in Royal Australian Air Force F/A-18 pilots and the implications for +Gz tolerance https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:11797 max) were determined in a sample of eight pilots using a progressive cycle ergometer protocol. Results: Of the 42 F/A-18 pilots who completed the questionnaire, 86% reported regular physical conditioning, mostly three times per week. Aerobic activities were the most common (83%), with running the most popular activity (55%). Anaerobic activities were reported by 26% of respondents. Most respondents reported doing more than one activity, with an average weekly training volume of 129 ± 77 min. The ergometer test results revealed a mean Vo₂max of 50 ± 6 ml 0₂ ·kg· min⁻¹ Condusion: The high rates of participation in regular physical activity suggest that physical fitness is perceived as important by the fighter pilot operating in the high +Gz environment. The fighter pilots in this study participated in aerobic activities at a much higher rate than anaerobic activities. The aerobic fitness levels measured suggest that the pilots have good but not exceptionally high levels of aerobic power that are unlikely to influence +Gz tolerance.]]> Sat 24 Mar 2018 08:13:10 AEDT ]]> Autonomic control of bronchial blood flow and airway dimensions during strenuous exercise in sheep https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12114 br) and dimensions during moderate and strenuous exercise, and to analyse the role of vagal and sympathetic nerves. Methods: Nine ewes (34–44 kg) underwent left thoracotomy during general anaesthesia (thiopentone/isoflurane) and either (5 sheep = Group 1) a pulsed Doppler transducer was placed on the bronchial artery, or (4 sheep = Group 2) a pulsed Doppler transducer was placed on the bronchial artery, and transit-time and single crystal sonomicrometers were mounted on the left main bronchus. These measured continuously Qbr, bronchial circumference (Circbr) and wall thickness (Thbr). Aortic pressure (Pa) and central venous pressure catheters were placed in the superficial cervical artery and vein. Trained sheep exercised on a horizontal treadmill, i.e. Group 1, moderate exercise 2.2 mph over 1.6, 6 min recovery, for analysis of changes in Qbr before and after cholinoceptor blockade; Group 2, strenuous exercise 4.4 mph over 2, 10 min recovery for analysis of changes in Qbr and airway dimensions, before and after cholinoceptor plus α1-, α2-adrenoceptor blockade. β-adrenoceptor systems were intact. Results: In Group 1 during moderate exercise Pa and heart rate (HR) rose. Qbr and blood flow conductance (Cbr) fell immediately to 83% (P<0.001) before returning toward resting levels, but fell when exercise ceased to 89% (P<0.01) before recovering. Prior cholinoceptor blockade abolished the immediate fall in Qbr and Cbr, but not the recovery vasoconstriction. Later in recovery the bronchial bed dilated progressively over 6 min (P<0.05). In Group 2 during strenuous exercise Pa and HR rose substantially. Qbr and Cbr fell to 68% and 54% (P<0.001), respectively, and there was early vasoconstriction in recovery. Circbr fell immediately and remained at 93% (P<0.01), and did not recover fully when exercise ceased. Thbr did not change during or after exercise. Prior cholinoceptor plus α-adrenoceptor block caused Pa and Qbr to fall slightly during exercise, but the bronchovascular constriction during and after exercise was abolished, as was circumferential shortening in the airway. Conclusions: At exercise onset and steady-state, resetting the arterial baroreflex upward in sheep increases parasympathetic cholinergic vasoconstrictor activity and causes bronchial wall and bronchovascular smooth muscle contraction in concert with sympathetic adrenergic constriction of systemic vascular beds. Whether the known sigmoid baroreflex control of tracheal smooth muscle tension at rest is extended to tracheobronchial smooth muscle and its circulation during exercise is yet to be determined.]]> Sat 24 Mar 2018 08:13:00 AEDT ]]> Recent views on integrated coronary control: significance of non-uniform regional control of coronary flow conductance https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12113 Sat 24 Mar 2018 08:12:59 AEDT ]]> Integration of baroreflex and autoregulation control of bronchial blood flow in awake dogs https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:11792 Q = 0.034 + 0.00033(XPg − 104.6). The regression fell on the line of equal proportional change. Conclusion: Baroreflexes do not functionally engage the autonomic outflow to the bronchial circulation. Under controlled conditions of systemic Pg change, the bronchial circulation is normally controlled by the integration of resting autonomic tone, myogenic autoregulation and pressure-passive effects.]]> Sat 24 Mar 2018 08:10:21 AEDT ]]> Using multiple response true-false multiple choice questions https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:11795 Sat 24 Mar 2018 08:10:21 AEDT ]]> Evidence of baroreflex adaptation to repetitive +Gz in fighter pilots https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:11791 Sat 24 Mar 2018 08:10:21 AEDT ]]> Integrated baroreflex control of regional coronary blood flow https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:11951 Sat 24 Mar 2018 08:09:41 AEDT ]]> Effects of graded exercise on bronchial blood flow and airway dimensions in sheep https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12192 br) and conductance (Cbr), bronchial circumference (Circbr) and wall thickness (Thbr). In Protocol 1 (P1), four sheep ran duplicate 5 min protocols on a horizontal treadmill at continuous step-up-and-down speeds of 1 min duration, namely, 0.8, 1.6, 2.2, 1.6 and 0.8 mph (moderate exercise), followed by 10 min recovery. In P2, four sheep ran duplicate 2 min protocols at constant 4 mph (strenuous exercise), and in P3, one sheep ran duplicate protocols each of 3 min at 2.2, 4.4 and 6 mph (severe exercise). Regression analysis and repeated measures ANOVA were used to assess differences between times, runs and exercise intensity. In P1, airway effects were directly related to graded exercise effort sustained over 5 min. Peak effects occurred at 2.2 mph, except for Thbr. Heart rate and Pa rose (to 156% and 111% of resting, respectively), and Qbr and Cbr fell (to 83% and 75%; both P<0.001). Circbr fell to 96% (P=0.02), and Thbr rose at low speeds early and late, and thinned at the highest speed. In P2 and P3 for all variables the steady-state effects were systematically greater than for P1 (4.4 mph: Cbr to 43%, Circbr to 93%; 6.6 mph: Cbr to 25%, Circbr to 82%). There was no significant recovery hyperaemia, but there was residual post-exercise bronchoconstriction. The exercise stimulus–response relationships from rest to a maximal 6 mph for sheep airway circumference and its bronchial circulation are inverse and functionally constrictor.]]> Sat 24 Mar 2018 08:08:28 AEDT ]]> Heart-lung interactions: the sigh and autonomic control in the bronchial and coronary circulations https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12191 Sat 24 Mar 2018 08:08:28 AEDT ]]> Disturbed hemodynamic cardiac exercise stress test response in non-smoking, normolipidemic, normotensive, diabetic subjects https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12193 Sat 24 Mar 2018 08:08:27 AEDT ]]> The effect of baroreflex adaptation on the dynamic cardiovascualr response to head-up tilt https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12190 Sat 24 Mar 2018 08:08:27 AEDT ]]> Control of resting bronchial hemodynamics in the awake dog https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12207 Sat 24 Mar 2018 08:08:25 AEDT ]]> Baroreflex control of coronary blood flow varies regionally in awake dogs https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12201 Sat 24 Mar 2018 08:08:24 AEDT ]]> Controlled trial of a minimal-intervention exercise program for middle-aged working women https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12202 Sat 24 Mar 2018 08:08:23 AEDT ]]> Cardiac afferent control of bronchial flow in awake dog https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:22754 BR), and intrapericardial (IPC) catheters were placed in pericardial sac for drug infusion. Arterial and central venous catheters were placed in omocervical vessels for measurement of blood pressures. IPC infusion of 2% procaine (16 mgkg-1) significantly (all P<0.05) raised resting heart rate (HR, to 210% of control), aortic pressure (Pa, 115%), QBR (146%) and bronchial flow conductance (CBR, 125%). In 6 dogs, IPC nicotine (0.5-16μgkg-1) produced transient bradycardia and hypotension, characteristic of vagal afferent stimulation in anesthetised dogs, before significantly (all P<0.05) raising HR (114%), Pa (121%), QBR (142%) and CBR(126%) 80 seconds after injection. IPC veratridine (2-20μg) significantly (all P<0.05) raised HR (134%), Pa(108%), QBR (164%) and CBR (155%) at 65 seconds. Responses to both stimuli were blocked by prior IPC application of procaine. The results suggest that cardiac sympathetic afferents tonically constrict the bronchial circulation at rest in the awake dog. Further, the chemical stimuli used cause non-specific activation of both sympathetic and vagal afferents to evoke a mixed cardiovascular response where a dilator mechanism prevails in the bronchial circulation, and a sympathoexcitatory effect in the systemic circulation. The findings are relevant to pulmonary congestion in heart failure syndromes.]]> Sat 24 Mar 2018 07:14:16 AEDT ]]> The need for steroids in modern athleticism https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12706 Mon 31 Aug 2020 16:16:31 AEST ]]> Public forum: "the drug-sport connection: should we be plugged in" https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12718 Mon 20 May 2019 11:15:37 AEST ]]> Limitation of a pulsed Doppler velocimeter for blood flow measurement in small vessels https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12206 10%. Distortion of pulsed Doppler signal peaks occurred in the conscious rabbit at peak aortic velocities, at which Reynold's number for turbulence was exceeded and the Doppler shift surpassed the Nyquist limit of 31.25 kHz for the velocimeter. Although the Doppler shift-volume flow relationship is linear at < 5 kHz, in some cases at higher Doppler shifts and blood flow velocities the relationship may become nonlinear, thus causing the volume flow rate to be underestimated by up to 38%. The cause of this phenomenon may be "aliasing" and/or the consequence of the range control capability of the velocimeter selectively sampling changing velocity profiles and flow disturbances in the central stream at higher velocities.]]> Fri 27 Sep 2019 16:32:00 AEST ]]> Differential effects of inhaled methacholine on circumferential wall and vascular smooth muscle of third-generation airways in awake sheep https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12405 br), Qbr conductance (Cbr), bronchial hemicircumference (CIRCbr), and bronchial wall thickness (WALL THbr) in recovered, standing, awake sheep. Methacholine (MCh; 0.125–2.0 μg/kg iv), at the highest dose, caused a 233% rise in Qbr (P < 0.05) and a 286% rise in Cbr (P < 0.05). CIRCbr fell to 90% (P < 0.05); WALL THbr did not change. In contrast, nebulized MCh (1–32 mg/ml), inhaled through a mask at the highest dose, caused a rise in ventilation and a rise in Qbr proportional to aortic pressure without change in Cbr. CIRCbr fell to 91% (P < 0.01), and WALL THbr did not change. Thus inhaled MCh has access to cholinoceptors of bronchial circumferential smooth muscle to cause airway lumen narrowing but effectively not to those of the systemic bronchovascular circulation. It is speculated that the mechanism is selective neuroparacrine inhibition of muscarinic acetylcholine receptors (M3 bronchovascular cholinoceptors) by prostanoids released by intense MCh activation of epithelial and mucosal cells lining the airway.]]> Fri 27 Sep 2019 16:25:54 AEST ]]> Thoracic resistivity for stroke volume calculation in impedance cardiography https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12664 τ) has been calculated in dogs from the rearranged Kubicek formula: pτ = (SV · Z02)/(L2 dZ/dtmax·T), where SV was measured by the electromagnetic flowmeter (EM). Hematocrit (Hct) in the dog was varied by hemorrhage and infusion. In contrast to the direct and exponential bench p-Hct relationship, pτ varies inversely with Hct, but by no more than +6.3 Ω · cm (at Hct 26%) and -11.8 Ω · cm (at Hct 66%) about a mean pτ of 135 ± 1.0 Ω · cm (at Hct 40%). Impedance SV calculated using pτ over a wide range of SV bears a linear relationship to EM values with a 95% prediction limit for a single SV estimate of ±0.84 about a mean value of 26.9 ml. The findings suggest that pτ is virtually constant during a variety of physiological disturbances.]]> Fri 27 Sep 2019 16:12:28 AEST ]]> The effects of altering ventricular rate on blood flow distribution in conscious dogs https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12670 Fri 27 Sep 2019 16:03:24 AEST ]]> Coronary dynamics in unrestrained conscious baboons https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12671 Fri 27 Sep 2019 15:57:40 AEST ]]> Central nervous system control of cardiorespiratory nasopharyngeal reflexes in the rabbit https://novaprd-lb.newcastle.edu.au/vital/access/manager/Repository/uon:12704 Fri 27 Sep 2019 15:45:17 AEST ]]>