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In order to determine if a positive water balance would impair cardiovascular and ventilatory adjustments during acute altitude exposure, six healthy male subjects were exposed to 4570 m for 2 h with and without water loading. No significant differences in any of the measured variables were observed between normal and overhydrated subjects. In order to(More)
This study was conducted to identify and clarify the actions of pulmonary and systemic H1- and H2-receptors by utilizing specific histamine receptor antagonists. Histamine was infused in anesthetized dogs during control conditions, after H2-receptor blockade with metiamide, after H1-receptor blockade with chlorpheniramine, and after combined H1- and(More)
There is a marked variability in the degree of pulmonary hypertension induced by long-term exposure to altitudes above 3000 m among low altitude species, ranging from hyporesponders (sheep and dogs) to hyper-responders (cattle and pigs). The amount of inherent muscularization of small pulmonary arteries appears to be a determinant of this hypertensive(More)
Persons with acute altitude sickness hypoventilate at high altitude compared with persons without symptoms. We hypothesized that their hypoventilation was due to low initial hypoxic ventilatory responsiveness, combined with subsequent blunting of ventilation by hypocapnia and/or prolonged hypoxia. To test this hypothesis, we compared eight subjects with(More)
The pulmonary hypertensive response to chronic hypoxia varies markedly among mammalian species. An explanation for this variability was sought by exposing seven species to hypobaric hypoxia (PB equal to 435 mmHg) for 19-48 days. Control animals were studied at 1,600 m (PB equal to 630 mmHg). The pulmonary hypertension that developed varied in the following(More)
We determined whether drugs which modulate the state of protein tyrosine phosphorylation could alter the threshold for high airway pressure-induced microvascular injury in isolated perfused rat lungs. Lungs were ventilated for successive 30-min periods with peak inflation pressures (PIP) of 7, 20, 30, and 35 cmH2O followed by measurement of the capillary(More)
The pulmonary vascular responses to acute hypoxia and to infusions of histamine and 5-hydroxytryptamine (5-HT) were recorded in unanesthetized standing bull calves under neutral (16-18 degrees C) and cold (3-5 degrees C) temperature conditions. Cold exposure alone resulted in a significant increase in pulmonary arterial wedge pressure from 10.2 +/- 3.5 to(More)
Studies of the cardiovascular response to lower body negative pressure (LBNP) in men and women have suggested that women may have less tolerance to LBNP than men, although tolerance per se was not determined. To investigate the effect of gender on tolerance to LBNP, 10 men 10 women were subjected to increasing levels of LBNP until presyncopal symptoms(More)
Thickening of peripheral pulmonary arteries (PA) in the pulmonary hypertensive neonate has been well described morphologically, but less is known regarding the role of cell proliferation in either the normal or hypertensive neonatal PA. Thus we studied DNA synthetic indices in the tunica media and tunica adventitia of four different sizes/generations of PA(More)