Possible Contributions of Endogenous Prostaglandins to the Control of Blood Pressure

Prostaglandins are primarily local or tissue hormones which have their effects at or near the site of release and are metabolized before reaching the arterial circulation. A possible exception is prostaglandin A2, which has been proposed as a circulating hormone; however, there is no evidence that prostaglandin A2 is biosynthesized in the mammalian kidney or even in extrarenal tissues. The prostaglandin generated and released in the kidney is predominantly E2. Some blood vessels also synthesize prostaglandins intra-murally, where their local release influences vascular tone and reactivity. Endogenous prostaglandin E2 production contributes to the regulation of blood pressure by (1) opposing the vasoconstrictor and antidiuretic actions of circulating pressor hormones; (2) braking the release of norepinephrine from vasoconstrictor nerves; and (3) participating in the control of extracellular fluid volume through its renal hemodynamic actions.