Intrarenal distribution of blood flow

Abstract

Clearances and extractions of para-aminohippurate were measured in normal dogs to investigate a proposal by Reubi for the approximation of the distribution of intrarenal plasma flow. The proposal equates the cortical plasma flow to the clearance of PAH, assuming that PAH is 100% extracted from the cortical flow. Medullary plasma flow is equal to the difference between total renal plasma flow and cortical plasma flow. Our evidence is consonant with this view. The distribution of plasma flow was so calculated during the intravenous infusion of 20% mannitol and during the infusion of acetylcholine or norepinephrine into the left renal artery. Mannitol and acetylcholine (50–80 µmoles/min) increased both cortical and medullary plasma flows and the total renal plasma flow. Medullary flow, however, increased proportionately more than cortical flow. Norepinephrine (38–9.0 µmoles/min) decreased cortical plasma flow and total renal plasma flow equally. Medullary flow did not change significantly.