Effects of prazosin on the cAMP system in the spontaneously hypertensive rat (SHR) aorta

3',5'-adenosine monophosphate (cAMP), adenylate cyclase and cAMP-phosphodiesterase (PDE) activity were measured in aorta homogenates from normal and spontaneously hypertensive rats (SHR) during treatment with prazosin, an antihypertensive drug. cAMP levels were lower in SHR than in normal rats. In SHR prazosin treatment induced marked inhibition of PDE activity thus causing an increase in cAMP levels; adenylate cyclase activity remained unaffected. This effect was only present for the first 32 days of drug administration.