Central injection of captopril inhibits the blood pressure response to intracerebroventricular choline.

In the present study, we investigated the involvement of the brain renin-angiotensin system in the effects of central cholinergic stimulation on blood pressure in conscious, freely moving normotensive rats. In the first step, we determined the effects of intracerebroventricular (icv) choline (50, 100 and 150 microg) on blood pressure. Choline increased blood pressure in a dose-dependent manner. In order to investigate the effects of brain renin-angiotensin system blockade on blood pressure increase induced by choline (150 microg, icv), an angiotensin-converting enzyme inhibitor, captopril (25 and 50 microg, icv), was administered 3 min before choline. Twenty-five microg captopril did not block the pressor effect of choline, while 50 microg captopril blocked it significantly. Our results suggest that the central renin-angiotensin system may participate in the increase in blood pressure induced by icv choline in normotensive rats.