Response of the Isolated Kidney to Acute Volume Expansion with Equilibrated Blood 1

Summary

The effect of acute volume expansion of a dog with equilibrated blood on sodium excretion in an isolated kidney perfused with blood from the volume expanded animal was examined. A significant increase in absolute and fractional sodium excretion was observed in the isolated kidney that could not be explained on the basis of changes in renal hemodynamics or physical factors and thus suggests that a humoral mechanism may have mediated the natriuretic response. The magnitude of the natriuresis was less than that previously reported when the isolated kidney was perfused with blood from a chronically DOCA and NaCl loaded animal. It is suggested that a humoral natriuretic mechanism may participate in the renal regulation of sodium balance and that the activity of this mechanism may undergo an adaptive increase in response to chronic extracellular volume expansion