Relationship between intrarenal distribution of blood flow and renin secretion during ureteral occlusion.

The present study was undertaken to evaluate the relationship between renin secretion from the denervated kidney and intrarenal distribution of blood flow during reductions in renal perfusion pressure by partial constriction of the aorta with and without ureteral occlusion in the anesthetized dog. In addition, renin contents in different zones of the kidney were measured. A reduction in renal arterial pressure from normal pressure (125-135 mmHg) to 77 mm Hg resulted in significant increase in renin secretion and redistribution of cortical blood flow. A further reduction of renal arterial pressure to 51 mmHg produced a marked increase in renin secretion rate (RSR) without further changes in the intrarenal distribution pattern of blood flow. The pressure reductions during ureteral occlusion increased RSR without any change in the distribution pattern of blood flow, and a decrease in the amounts of extractable renin was found in the outer cortex of the experimental kidney. These findings suggest that renin release occurs mainly in the outer cortex, and this process may be stimulated when the mechanism of autoregulation fails as the perfusion presure approaches to the lower range of autoregulation in the outer cortex.