Diminished total renal blood flow in hypertensive patients is primarily due to a reduction in cortical flow and cortical blood volume, with preservation of medullary flow.
Supports cortical predominance in hypertensive TRBF reduction; leaves open whether medullary preservation affects progression or guides imaging.
In 15 patients with essential hypertension total blood flow to a single kidney (TRBF) was measured by a constant infusion indicator-dilution technic which had previously been validated in dogs. Indocyanine green indicator-dilution curves then were used to calculate the fraction of renal flow traversing the rapid (cortical) circulation and the blood volume in this cortical compartment. TRBF ranged from 152 to 1033 ml/min/1.73m 2 per kidney and was closely correlated with cortical flow (r = 0.99). The cortical fraction of TRBF ranged from 46 to 93% and varied directly with total flow (r = 0.69). Noncortical flow ranged from 12 to 85 ml/min/1.73m 2 per kidney and showed no correlation with TRBF. Cortical blood volume varied from 12 to 85 ml/1.73m 2 and also was closely correlated with TRBF (r = 0.93). These data suggest that diminished TRBF in hypertensive patients is due to reduction in cortical flow with preservation of noncortical (medullary) flow and reduction in cortical blood volume. The reduced cortical fraction of TRBF could be a factor in the renal functional abnormalities which occur in hypertension.
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Logan et al. (1973) studied this question.
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