Autonomic Nerves Versus Prostaglandins in the Control of Rat and Rabbit Testicular Capsular Contractions in vivo and in vitro1

The tonus and rate of spontaneous contractions measured in vivo from the tunicaalbugineaof rabbit testes were augmented by epinephrine, acetylcholine and prostaglandin (PG)F2 �. Neither reserpine, dibenamine nor atropine decreased autorhythmic contractility. Indomethacin injections ip significantly decreased the mean amplitude of testicular contractions. This treatment effaced motility in two of eleven preparations. Injections of 5,8,11,14-eicosatetraynoic acid (TYA) did not significantly decreasetheamplitudeof contraction. Electrical stimulation of the spermatic artery (site of thespermaticnerve) in rabbits and in rats failed to alter testicular tonus or motility. The above evidence suggests that local factors such as PG5 may contribute more to smooth muscle activity in the tunica albuginea of rabbittestesthan do autonomic nerves. The rhythmical contractions observed in vivo, however,continuedinthe presenceof indomethacin in the bathing medium, and may not requirestimulationby PG5 fortheirorigination. Rat testes, unlikerabbit testes, did not contract rhythmically in vivo. Isolated rat testescontractedin responseto administered PGF20, while PGE1 abolished the induced contraction. Such modulators of muscular tonus feasibly could alter intratesticular pressure for the intact animal.