Release of prostaglandin I2 from hog kidney by propranolol

Prostaglandin I2 (PGI2) decreases blood pressure. Perfusion of isolated hog kidney by propranolol in modified Krebs-Ringer solution resulted in a significant increase in 6-keto-prostaglandin F1 alpha, the major metabolite of PGI2. Prostaglandin E2 and renin activity remained unchanged. Because the concentration of PGI2-like substance in the renal vein has been shown to be greater than in the renal artery after bradykinin infusion, a contribution of PGI2 to the regulation of blood pressure was proposed. Isoproterenol has been shown to augment urinary kallikrein, but the effect of urinary kallikrein on propranolol is unclear. With a modified Krebs-Ringer solution free of plasma kininogen, a renin substrate, it was concluded that propranolol (1) induces PGI2 release from the kidney, which may contribute to a direct antihypertensive action of this beta-adrenergic blocking agent, and (2) decreases urinary kallikrein.