Abstract
Summary
Previous studies of hypoxia induced alterations in renal function have yielded conflicting results. Uncontrolled acid base conditions in most studies may account for this scatter. To eliminate acid-base effects hypoxia was induced in dogs while arterial pCO2 and pH were maintained constant for 60-90 min. To test whether the effects of hypoxia were mediated by vasoconstriction or ischemic injury, acetylcholine was infused unilaterally into one renal artery. During hypoxia the GFR and RPF of the kidney not receiving acetylcholine decreased significantly. In the kidney perfused with acetylcholine, however, GFR and RPF did not change. Sodium excretion fell in nonperfused but did not change significantly in acetylcholine perfused kidneys. Using the radiomicrosphere method, fractional distribution of renal cortical blood flow was found to be unaffected by hypoxia. The data demonstrate that acute hypoxia reversibly decreases GFR and RPF by functionally increasing renal vascular resistance uniformly throughout the kidney and that these changes were associated with a decrease in sodium excretion.
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