The Effects of Ganglion‐blocking and Postganglionic Sympatholytic Drugs on Preparations of the Guinea‐pig Vas Deferens

Abstract

The contractions of the guinea-pig isolated vas deferens elicited by electrical stimulation of the hypogastric nerve were completely blocked by the following drugs: guanethidine, bretylium, dimethylphenylpiperazinium hydrochloride, nicotine, pempidine, hexamethonium, hemicholinium, D-tubocurarine and procaine. However, when the vas deferens was stimulated through an electrode in its lumen, the contractions in response to frequent, short stimuli (50 shocks/sec, I msec duration) were blocked by guanethidine, bretylium and dimethylphenylpiperazinium, but were not affected by the remaining drugs, except that procaine and hemicholinium each caused some reduction in the responses.When the preparation was stimulated transmurally with shocks of 200 msec duration at 1 shock/sec, the contractions were unaffected by any of the above drugs, except hemicholinium which again caused a slow reduction of up to 50% of the original response. It is concluded that nicotine, pempidine, hexamethonium, D-tubocurarine and hemicholinium probably block the response to stimulation of the hypogastric nerve by acting on peripheral ganglia in its pathway. Hemicholinium appears to have an additional effect in depressing the responses of the smooth muscle of the vas deferens to direct electrical stimulation, and procaine may act both on the ganglia and at the nerve terminals.

A comparison of the sensitivities of innervated and denervated rat vasa deferentia to agonist drugs

“…It has been reported (Bentley & Sabine, 1963;Thoa & Maengwyn-Davies, 1968) that simply stripping away the serous coat after removing the vas deferens from the animal increases the sensitivity of the vas to drugs by facilitating access to the smooth muscle cells. It may be that some of the increase in sensitivity to nor--adrenaline and to adrenaline found after denervation can be accounted for on this basis.…”

The Possibility That Adenosine Triphosphate Is an Excitatory Transmitter in Guinea-Pig Seminal Vesicle

“…(1-4), the adrenergic nature of which has been shown by many investigators (5)(6)(7)(8)(9)(10). How ever, a persistent resistance to various adrenergic a-blocking agents, such as tolazoline and phenoxybenzamine, both in vitro (10-12) and in vivo (13) still remained unexplained.…”

Ganglionic Blockade by Rhazidine

“…in the cat a.s well as va.s deferens preparations stimulated through hj'pogastric and intramural nerves in the guinea-pig. It is established that most of the fibres in tlie hypogastric nerve art> pre-ganglionic {Sjostraiid, 1962; Bentley and Sabine, 1963;Kuriyama, 1963;Ohlin and Strombland, 1963;Birmingham and Wilson, 1963), whereas responses of the vas deferens to intramural stimulation are through post-ganglionic s\7npathetic nerve ending.s (Birmingham and Wilson. 1963).…”