Adrenergic and serotonergic receptor-blocking potencies of terazosin, a new antihypertensive agent, as asseased by radioligand binding assay.

Publisher Website
Google Scholar
Abstract
To assess the antihypertensive effect of terazosin, 2-[4-(tetrahydro-2-furanyl)carbonyl-1-piperazinyl]-6,7-dimethoxy-4-quinazolinamine hydrochloride dihydrate, the inhibitory potency of terazosin on 3H-prazosin, 3H-p-aminoclonidine, 3H-dihydroalprenolol (3H-DHA), 3H-serotonin and 3H-ketanserin bindings to .alpha.1-, .alpha.2- and .beta.-adrenergic receptors and 5HT1 and 5HT2 (serotonergic) receptors was examined by using the radioligand binding method. The results were compared with those for prazosin and bunazosin. Dog brain and aorta were used in the present study. A high inhibition of 3H-prazosin binding to .alpha.1-adrenoceptors in dog aorta by terazosin was observed, but the inhibitions of 3H-prazosin binding to .alpha.1-adrenoceptors in dog aorta by terazosin was observed, but the inhibitions of 3H-DHA, 3H-p-aminoclonidine, 3H-serotonin and 3H-ketanserin bindings by this drug were very weak. l-Terazosin showed the greatest inhibitory effect on 3H-prazosin binding to .alpha.1-adrenoceptors in dog aorta and brain. These results suggest that an inhibitory effect of terazosin at .alpha.1-adrenoceptor binding sites may contribute to the hypotensive effect; the .alpha.2- and .beta.-adrenoceptors and the serotonergic binding sites do not appear to be involved.