[Quantitative analyses of human prostatic alpha-adrenoceptors and effects of terazosin on the alpha-adrenoceptor activity].

The adrenergic alpha-1 and -2 adrenoceptors in human hypertrophied and non-hypertrophied prostatic adenomas were measured in the saturation experiment using 3H-prazosin and 3H-yohimbine. Not only alpha-1 adrenoceptor but also alpha-2 adrenoceptor were found to exist with great amount in prostatic adenomas. In the inhibition experiment selective alpha-1 antagonists, prazosin and terazosin inhibited the 3H-prazosin or 3H-yohimbine bindings to prostatic adenomas. The ability as alpha-1 antagonist is ten times greater in prazosin than in terazosin, but that as alpha-2 antagonist is greater in terazosin than in prazosin. These data suggest that terazosin may have other effects than the relaxation of prostatic smooth muscles in hypertrophied prostatic adenoma.