Abstract
Summary
The spontaneous contractions that occur in rabbit testes in vitro were abolished by changing the bathing medium. Adding the initial medium from an active to an inactive preparation induced activity in the inactive testis. Extraction of the initial medium at pH 3 into ethyl acetate, a system used for recovering prostagandins, yielded a residue that restored the activity. Acetylcholine and serotonin had little effect on the inactive preparation nor could a smooth-muscle active substance be extracted from these preparations. Oxytocin stimulated neither the active nor the inactive testis appreciably. Epinephrine increased tonus in both inactive or active preparations, but did not induce rhythmic contractions. Prostaglandins of the E-type were stimulatory at low, but inhibitory at higher concentrations. A myogenic agent with prostaglandin-like properties was present only in the bathing media from active preparations and appeared to determine the response that was obtained by treatment with exogenous prostaglandins or some pharmacological agents in vitro.
This work was supported by U. S. Atomic Energy Commission Grant No. AT(11–1)–1602 and Utah State University Research Grant U-300. We thank Dr. John E. Pike, Upjohn Co. for the generous contribution of the prostaglandins.
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