Endogenous inhibition of the mechanical response of the isolated rat and guinea-pig vas deferens to pre- and postganglionic nerve stimulation.

Abstract

AbstractRepeated periods with prolonged nerve stimulation (30 s) of the isolated vas deferens tended to depress especially the initial, rapid phase of subsequent contractions.The following findings led to the conclusion that the inhibition was induced by prostaglandin (PG)‐like material, released from the organ on nerve stimulation: 1. The inhibition was immediately abolished on washing of the organ. 2. It appeared faster in an organ bath of small volume than in one of a greater. 3. It was possible to transfer the substance from one bath to influence an organ in another. 4. The inhibitory agent, like exogenous PG, influenced both phases of contraction, the second, however, to a less extent. 5. The ganglionic transmission in the last part of the hypogastric nerve was found to be extremely sensitive to the inibitory substance as to exogenous PG (0.1–0.4 ng/ml). 6. In vitro inihibition of PG synthesis led to a partial or total abolishment of the endogenous inhibition. 7. Release upon nerve stimulation of PG‐like material, mainly PGE2, was established.It is suggested that this endogenous inhibiting process might play a modulating role in the nerve‐induced mechanical activity of this organ also under in vivo conditions.