We evaluated the effects of hemodilution, expansion of intravascular volume, and expansion of interstitial volume on the distribution of cortical renal blood flow, utilizing the microsphere technique. Hemodilution without volume expansion (saline exchange) produced an increase in fractional blood flow in zone 1 (outermost zone) of the cortex from 34 plus or minus 1% to 43 plus or minus 2% and a...