INFLUENCE OF LOWERED TEMPERATURE UPON THE RESPONSE OF PROSTATIC AND EPIDIDYMAL PORTION OF THE RAT ISOLATED VAS DEFERENS TO FIELD STIMULATION

This paper reports the effects of lowering (bath) temperature upon contractile responses of prostatic and epididymal ends of the rat isolated vas deferens to electrical field stimulation. Responses to field stimulation with single pulses at 60 s intervals were potentiated by lowering the bath temperature. This effect was maximal at temperatures of 25-27 degrees C and was reduced in preparations treated with phentolamine (5 mumol/l). Field stimulation with trains of 50 pulses at 5 Hz every 5 min produced biphasic contractions of preparations. The initial, twitch-like component, prominent at the prostatic end and resistant to blockade by phentolamine (5 mumol/l) was little affected by lowering the bath temperature from 37.5 degrees C to 19 degrees C. In contrast, the second, more prolonged, component of the response to pulse trains, which was prominent at the epididymal end of the tissue was decreased by lowering the bath temperature and by phentolamine. In the epididymal segment, responses to exogenous noradrenaline were enhanced by lowering the bath temperature. It is concluded that lowering the bath temperature enhances the contractility of the vas deferens in response to the release of neurotransmitters and to the application of exogenous noradrenaline via a postsynaptic action. In addition, via a presynaptic action, lowering the bath temperature depresses or delays the release of the noradrenergic transmitter from the sympathetic nerve terminals.