An investigation of the actions of the calcium entry facilitator Bay K 8644 on the rat vas deferens.

The pre- and postsynaptic actions of the calcium entry facilitator Bay K 8644 were investigated in the rat isolated vas deferens. Bay K 8644 had no presynaptic effect on adrenergic neurotransmission in the epididymal portion. Bay K 8644 and alpha 1-adrenoceptor agonists potentiated, and the calcium entry blocker nifedipine abolished, the non-adrenergic contraction to a single stimulus in prostatic portions. Bay K 8644 sensitised the prostatic portion to, but did not increase the maximum height of, spontaneous direct contractions produced by alpha-agonists.