Regulation of the acid-base balance during prolonged hypoxia: effects of respiratory and non-respiratory acidosis.

Abstract

Prolonged hypoxia results in adaptive changes in the oxygen transfer system which appear to be designed to insure adequate oxygen supply to the cells (for review, see Bouverot, 1985). Many of these adaptations, however, produce other functional changes not directly concerned with oxygen transfer. Examples of this are the acid-base changes of high altitude hypoxia. Fig. 1 shows the time course of changes in plasma acid-base balance in male conscious rats exposed to a barometric pressure of 370-380 torr (Gonzalez and Clancy, 1986a). The hyperventilation initially results in respiratory alkalosis; this is eventually corrected by a proportionate decrease in plasma [HCO 3 - ], which is largely due, in turn, to the renal compensatory mechanisms put into motion by the alkalosis. After three weeks of hypoxia, plasma pH has returned to normal, but at the expense of depletion of HCO 3 - .