Hypoxic pressor responses in lungs from rats acutely exposed to simulated high altitude.

Male Sprague-Dawley rats were exposed to 6, 3 or 1 h of simulated high altitude (380 Torr). The isolated perfused lung of each animal was challenged with 4 sequential periods of hypoxia, angiotensin II (AII), and 5-hydroxytryptamine (5-HT) following altitude exposure. Isolated perfused lungs of low altitude control rats were similarly challenged. The acute hypoxic vasoconstrictor response was significantly reduced in animals exposed to 3 and 6 h of high altitude compared to low altitude control animals. The hypoxic pressor response was not significantly different from control in animals exposed to 1 h of simulated altitude. Pressor responses to AII and 5-HT following altitude exposure were not significantly different from controls.