Effects of captopril and prostaglandin I2 on vasoconstrictor responses to norepinephrine and potassium ions in rat mesenteric artery.

In the perfused rat mesenteric vascular bed, the effects of captopril and prostaglandin I2 (PGI2) on the vasoconstrictor responses to norepinephrine or potassium chloride were studied. Captopril or PGI2 in the perfusate attenuated the vascular responses to norepinephrine in a dose-related manner, while these substances had no effect on the vascular contractions induced by potassium chloride. In preparations treated with indomethacin, the inhibitory effect of captopril on the vascular response to norepinephrine was similar to that found in the untreated preparations. These results suggest that, although the effects of captopril on the vascular reactivity is similar to that of PGI2, the direct vascular action of captopril is not mediated by the synthesis of prostaglandins in the vascular bed.