Dependency of hypoxic pulmonary vasoconstriction on temperature.
We studied the effect of temperature change on hypoxic pulmonary vasoconstriction. Selective hypoxia on the left lower lobe of the lung in open-chested dogs at 37 degrees C caused the electromagnetically measured blood flow to the lobe to decrease 51 +/- 5 (SE)% and its vascular resistance to increase 155 +/- 25%. Testing hypoxic response. The hypoxic response at 31.1 +/- 0.4 degrees C was only a 26 +/- 6% decrease in lobar blood flow compared to the hypoxic response at 40.0 +/- 0.5 degrees C which was a 60 +/- 5% decrease in lobar blood flow. Hypothermia itself was associated with a significant increase in pulmonary vascular resistance. We conclude that hypothermia inhibits and hyperthermia enhances hypoxic pulmonary vasoconstriction. The mechanism of inhibition may involve prehypoxic vasoconstriction.
D000818:Animals; D001794:Blood Pressure; D001831:Body Temperature; D002302:Cardiac Output; D004285:Dogs; D006439:Hemodynamics; D000860:Hypoxia / Q000378:metabolism*; D008168:Lung / Q000098:blood supply*; D014655:Vascular Resistance; D014666:Vasomotor System / Q000378:metabolism*