Effects of autonomic drugs on contractions of rat seminal vesicles in vivo.

Various autonomic drugs were placed on the peritoneal covering of the seminal vesicles of anaesthetized rats. Adrenaline (which stimulates the alpha-, beta 1- and beta 2-adrenoceptors) and phenylephrine (an alpha-stimulating agent) produced a sudden increase in tonus and in the amplitude and frequency of contractions. Phentolamine (an alpha-blocker) prevented these effects, whereas propranolol (a beta 1- and beta 2-blocker) did not. Phentolamine also abolished the seminal vesicle response to electrical stimulations. Terbutaline (a beta 2-stimulating agent) did not affect the spontaneous activity. There were no differences between the effects of terbutaline alone and those of terbutaline in the presence of propranolol. Moreover, propranolol did not block the contractile response of the gland to adrenaline or to electrical stimulation. These results indicate that alpha-adrenergic receptors are present in the muscle cell membrane of the rat seminal vesicle. The effects of acetylcholine were similar to those produced by adrenaline or phenylephrine although of smaller magnitude. Atropine prevented the effects of acetylcholine, indicating that they are of the muscarinic type.