The effect of PGH 2 on blood flow in the canine renal and superior mesenteric vascular beds

Abstract

Effects of the prostaglandin endoperoxide, PGH 2, were investigated in the renal and superior mesenteric vascular beds in anesthetized dogs. Vascular effects of a stable PGH 2 analog were also studied in the intestine. Blood flow was measured with electromagnetic flowmeters and vasoactive hormones were administered by close intra-arterial injection. Authentic PGH 2 increased blood flow in the kidney and intestine in a dose-related manner. Mesenteric blood flow was reduced by the PGH 2 analog in a dose-dependent fashion which was similar to the vasoconstrictor activity of norepinephrine in this organ. PGH 2 is biologically unstable and the type and activity of its metabolic products may vary in different regional vascular beds. Most of the known products of PGH 2 metabolism in the kidney are vasodilators whereas in the intestine both vasodilator and vasoconstrictor metabolites are formed. It has been suggested that the vascular activity of PGH 2 in an organ is dependent on the predominant type and activity of specific terminal enzymes that convert PGH 2 to its various vaso-active products.