Effects of prostacyclin infusion on blood pressure and plasma renin activity in patients with essential hypertension.

The effects of prostacyclin infusion (6.7 +/- 2.7 ng/kg/min, 3 to 10 ng/kg/min) on blood pressure, plasma renin activity (PRA), and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) were studied in 7 patients with essential hypertension (4 men and 3 women) with a mean age of fifty-eight +/- eleven years (forty-six to seventy-four years). The baseline value of 6-keto-PGF1 alpha for patients with essential hypertension was not lower than in healthy subjects. Blood pressure immediately dropped following prostacyclin infusion. Systolic blood pressure returned to the baseline value after prostacyclin infusion was discontinued. However, diastolic blood pressure and mean arterial blood pressure were still significantly decreased thirty minutes after termination of infusion. Heart rate did not change during prostacyclin infusion but decreased significantly when infusion was terminated. PRA was not significantly affected by prostacyclin infusion. The 6-keto-PGF1 alpha level was about 8 times higher than the baseline value thirty minutes after initiation of prostacyclin infusion and approximately twice as high as the baseline value thirty minutes after termination of infusion. The decrease in mean arterial blood pressure coincided with the increase in 6-keto-PGF1 alpha. There was no correlation between mean arterial blood pressure and PRA, nor between PRA and 6-keto-PGF1 alpha. These results demonstrate that production of prostacyclin is not reduced in patients with essential hypertension, and heart rate and PRA are not changed by prostacyclin infusion, although prostacyclin decreases blood pressure.