CONTRACTILE RESPONSES OF PROSTATIC AND EPIDIDYMAL PORTIONS OF ISOLATED RABBIT VAS DEFERENS TO ELECTRICAL FIELD STIMULATION

Abstract

The prostatic and epididymal portions of rabbit vas deferens were different in the reactivity to electrical field stimulation (EFS), adenosine triphosphate (ATP) and noradrenaline (NA). The EFS produced biphasic contractile response; VIZ. the first rapid twitch like (phasic) and the second slow sustained (tonic) contraction. The ratio of the amplitude of the phasic contraction to that of the tonic contraction in response to the EFS was higher in the prostatic portion than that in the epididymal portion. The increase of stimulation frequency from 5 to 10 and 20 Hz more markedly augmented the tonic contractile response than the phasic contractile response. Then, the ratio of the amplitude of the phasic contraction to that of the tonic contraction decreased according to the increase of the stimulation frequency. The tension development of the phasic and the tonic contractile responses to the EFS in the prostatic portion was significantly larger than those in the epididymal portion. The administration of 1 mM ATP produced phasic contraction. The contractile response to 1 mM ATP was more remarkably appeared in the prostatic portion than in the epididymal portion. The administration of 10 microM NA produced slow sustained tonic contraction, which also more markedly appeared in the prostatic portion than in the epididymal portion. The findings may indicate that the prostatic portion of rabbit vas deferens was more strongly innervated by purinergic nerves, and had higher reactivity to EFS, ATP and NA than the epididymal portion.