Relationship between collateral development and renin in experimental renal arterial stenosis.

Lateralizing renal venous plasma renin activity (RVPRA) ratios offer a predictive index of success of revascularization procedures for renovascular hypertension. Reliance upon nonlateralizing renin ratios to reject functional significance of renal arterial stenosis may deny some patients benefit of successful operations. To test the hypothesis that RVPRA ratios revert toward unity coincident with development of collateral circulation to an ischemic kidney, the relationship between development of collaterals and RVPRA was studied in nine dogs after gradual unilateral renal arterial occlusion with a constrictor. Arterial blood pressure and arteriographic measurement of collateral channels, RVPRA, and renal surface index (RSI) were measured before and during the 10-week interval after constrictor placement. RSI measurements, documenting changes in volume of the renal parenchyma, reflected changes in renal blood flow. Arterial pressure increased in each animal (p less than 0.0009). The number of collateral vessels to the constricted kidney increased with time (p less than 0.01). During the 4 weeks following placement of the constrictors, RSI ratios (constricted: nonconstricted) decreased (p less than 0.003) and RVPRA ratios (constricted: nonconstricted) increased (p less than 0.005). Subsequently, coincident with development of collateral vessels, RSI ratios increased and RVPRA ratios decreased toward control values. These data suggest that absence of lateralizing RVPRA ratios in the presence of collateral vessels does not mean lack of functional significance of stenotic renal arterial lesions.