Enhanced renal prostaglandin production in the dog. II. Effects on intrarenal hemodynamics.

The effects of enhanced endogenous production of prostaglandins by the kidney on the distribution of blood flow in the renal cortex were assessed by infusing sodium arachidonate, the precursor of the renal prostaglandins, into one renal artery of the dog. The changes produced with arachidonate (3 times 10--6 g/kg min-1 and 10--5 g/kg min--1) were compared with those produced by infusions of prostaglandin (PG) E2 (10--7 g/kg min--1) and PGF2alpha (3 times 10--7 g/kg min--1) into one renal artery. Distribution of renal blood flow was measured by the radioactive microsphere technique. Sodium arachidonate caused an increase in blood flow to the inner cortical zones with no change in flow to the nephrons in the outermost quarter of the cortex. PGE2 increased flow to all cortical zones, and PGF2alpha produced no change in flow. Since arterial blood pressure did not change, changes in vascular resistance were reciprocal to changes in flow. Thus, vascular resistance fell in the inner cortical regions but not in the outer regions, with arachidonate infusions and in all regions of the cortex with PGE2 infusions; no changes were seen with PGF2alpha infusions. These data indicate that prostaglandin formed endogenously in the kidney affects the vascular resistance of only the inner cortical nephrons; the data thus support the hypothesis that renal prostaglandins are one mediator of renal autoregulation of blood flow.