The Possibility that Adenosine Triphosphate is an Excitatory Transmitter in Guinea-Pig Seminal Vesicle

Guinea-pig seminal vesicle, like the vas deferens, is innervated by hypogastric nerves (1–4), the adrenergic nature of which has been shown by many investigators (5–10). However, a persistent resistance to various adrenergic α-blocking agents, such as tolazoline and phenoxybenzamine, both in vitro (10–12) and in vivo (13) still remained unexplained. On the other hand, Swedin (14) has demonstrated a biphasic mechanical response of guinea-pig vas derefens to relatively long periods (30 sec) of nerve stimulation; the initial “twitch” response was potentiated by adrenergic α-blocking agents, while the second phase of the contractile response was depressed or prevented. Ambache and Zar (15) have argued that the motor transmission in guinea-pig vas deferens is not adrenergic. The present study was undertaken to investigate the effect of adenosine 5’-triphosphate disodium (ATP) on isolated guinea-pig seminal vesicle, it being known that hypogastric nerve fibers innervating bovine vas deferens and seminal vesicle contain a considerable amount of ATP (16).