A study of alpha adrenergic receptors in human and rabbit corpus cavernosum tissue / 대한비뇨기과학회지

ABSTRACT

The relaxation of the corpus cavernosum smooth muscle, which is main process in penile erection, is controlled by nerves that release cholinergic and nonadrenergic-noncholinergic neurotransmitters as well as vascular endothelium derived relaxing factor(EDRF). But the adrenergically-induced tone maintains the penis in flaccid state. In order to define the physiological role of adrenergic neurotransmission in the local control of penile erection we studied the distribution of alpha adrenergic receptor subtypes and their pharmacological potency in human and rabbit corpus cavernosum tissue. In this study we used yohimbine as the alpha-2 antagonist, which is known to have beneficial therapeutic effect for organic impotence, to assess its neuropharmacological mechanism in the treatment of erectile dysfunction. The alpha-1 alpha-2 receptor potency was approximately 7.41 and 2.21 in human and rabbit tissue respectively. These results indicate that the predominant alpha adrenergic receptor is alpha-1 type and alpha-2 receptor antagonist, yohimbine, can not play a main role on the local control of penile erection because of its low receptor potency especially in human corpus cavernosum tissue. It remains possible that yohimbine partially antagonizes the postsynaptic alpha-1 mediated effect or activation of central sympathetic pathway is necessary for the therapeutic effect of yohimbine in human.