The effect of Enalapril on PGI(2) and NO levels in hypertensive patients

The effects of the angiotensin-converting enzyme inhibitors (ACEIs), may be partially mediated by the kinins' paracrine influence. Their actions may be exerted through nitric oxide and prostacyclin (PGI(2)) synthesis stimulation. The aim of our study was to determine whether the antihypertensive effect of Enalapril correlated with the increment in the plasmatic levels of NO and PGI(2) in essential moderate hypertensive patients. Normalization of blood pressure was observed in 20 patients, four on the 28th day, 15 on the 42th day and one on the 56th day. Enalapril-respondent subjects showed increased nitrate/nitrite levels on the 14th day (30% increment), on the 28th day (64%), on the 42th day (93.5%) and on the 56th day (96.2%) compared with basal levels, but they did not modify the circulating 6-keto PGF(1 alpha) levels. Four non-respondent patients showed a diminution in nitrate/nitrite and 6-keto PGF(1 alpha) circulating levels along the treatment. We conclude that the administration of 5-30 mg of Enalapril increases circulating NO metabolites in respondent-essential hypertensive subjects. The lack of responsiveness to the treatment may be related to the presence of risk factors such as those linked to an increase of oxidative stress. Finally, we consider that the evaluation of circulating NO may represent a predictive of the response to Enalapril in essential hypertensive patients.