THE EFFECT OF CHANGES IN HYDROGEN ION CONCENTRATION ON THE PULMONARY CIRCULATION*

Abstract

Acute acidosis whether induced by infusion of fixed acids or by the controlled breathing of 5% CO2, consistently elicited pulmonary vasoconstriction in the anesthetized dog. However, acute alkalosis, induced by either tris-hydroxymethyl-aminomethane or NaHCO3, failed to produce vasodilatation or to modify the pulmonary arterial pressor response to hypoxia. These experiences indicate that acute hypercapnia elicits pulmonary vasoconstriction through the acidosis it produces, whereas acute hypoxia appears to be a stimulus to pulmonary vasoconstriction which is independent of the hydrogen ion concentration.