射精の研究

第5報 射精に対する自律神経薬剤の影響について

抄録

The effects of autonomic drugs on seminal emission and ejaculation were investigated in mongrel dogs. Changes in the posterior urethral pressure (Posterior Urethrogram) and the volume of seminal emission during continuous hypogastric nerve stimulation were measured in different dogs. The seminal emission induced by hypogastric nerve stimulation caused continuous rise in the posterior urethral pressure. When the pressure reached the maximum level, a rhythmic alteration of the pressure which was considered to be a phenomenon identical to ejaculation occurred. The drugs were administered into the aorta close to the bifurcation.
The following results were obtained: Tetrodotoxin (1-5μg) abolished both seminal emission and rhythmic alterations of the posterior urethral pressure. Phenylephrine (10-100μg) and methoxamine (10-30μg) markedly increased the seminal emission and induced the rhythmic alterations. Phentolamine (1-10mg) and phenoxybenzamine (1-10mg) abolished both seminal emission and the rhythmic alterations. Administration of isoproterenol (10-30μg) or propranolol (1-10mg) affected neither seminal emission nor the rhythmic alterations. Acetylcholine (1-10μg) or atropine (1-10μg) did not show any definite effect on both seminal emission and on the rhythmic alterations. No significant effect of DMPP (10-30μg) on seminal emission or on the rhythmic alterations was observed. No significant change in seminal emission was caused by hexamethonium (100-500μg). The rhythmic alterations were not affected by the agent in most dogs.
From these results it is concluded that both semiqal emission and ejaculation are predominantly under the influence of the adrenergic nervous system, particularly through an α-adrenergic receptor mechanism.