KCL CONTRACTIONS IN THE RAT INTACT AND BISECTED VAS DEFERENS: CONTRIBUTION OF ENDOGENOUS NORADRENALINE RELEASE

1 KCl produced a biphasic contraction in the intact rat vas deferens. Both components were larger and the initial rapid phasic component was faster in the prostatic portion than the epididymal portion. In some experiments the epididymal phasic response was a single slow contraction, while in others it had a mixture of fast and slow responses. 2 Phentolamine reduced the phasic response but not the tonic response of the intact vas deferens. This effect was not observed after denervation produced by chronic guanethidine treatment. 3 Both phases of the response to KC1 160 mmol/1 were substantially reduced by phentolamine in the epididymal portion. In the prostatic portion phentolamine produced only slight inhibition of the phasic component and had no effect on the tonic component. 4 Isoprenaline had no effect on the response to KC1160 mmol/1 but reduced both phases of the response to KC150 mmol/1. This effect was antagonized by propranolol. 5 It is concluded that part of the phasic component of the response to KC1 in the rat vas deferens is due to the release of noradrenaline from intramural nerves.