Effect of indomethacin on responses to [sar-ileu]-angiotensin II

The role of prostaglandins in immediate and sustained pressor responses to [sar-ileu]-angiotensin II was studied, using indomethacin, in 12 patients with essential hypertension. Blood pressure rose within 1 to 2 min, peaked in 4 to 8 min, then fell gradually, but did not return to the baseline level, at the end of 30-min infusion period of the angiotensin II analogue. After 2 days on indomethacin, both immediate and sustained diastolic pressure responses to the analogue (both, P less than 0.01) rose when the basal plasma renin activity (PRA) fell (P less than 0.05); this was associated with 56% suppression of urinary prostaglandin E excretion. Both the immediate and late phases of blood pressure response may be affected by indomethacin, probably not only because of greater availability of angiotensin receptors due to decrease endogenous angiotensin, but also because of alteration of end-organ sensitivity to angiotensin II through inhibition of prostaglandin synthesis. This speculation is supported by the difference in slopes of the regression line relating change in diastolic blood pressure to basal PRA, indicating that there is less effect on controls for a given PRA level than on treated subjects.