Changes in electrophysiological properties in the prostatic portion of vas deferens from spontaneously hypertensive rats.

Abstract

The main objective of this study has been to analyse the electrophysiological differences in the prostatic portion of vas deferens between spontaneously hypertensive (SHR) and Wistar Kyoto rats (WKY). Resting membrane potentials (RMP) recorded in SHR (-63.8+/-0.3 mV) and WKY (-68.1+/-0.3 mV) were significantly different. Bath applications of suramin (30 microM), alpha,beta-methylene adenosine 5'-triphosphate (alpha,beta-meATP; 30 microM) or prazosin (0.1 microM) did not modify the control values of RMP. In control conditions, spontaneous excitatory junction potentials (SEJPs) were recorded in preparations from both groups of animals. SEJPs registered in SHR were greater than those in WKY in amplitude (7.0+/-0.4 mV vs. 2.6+/-0.1 mV) and frequency (0.25+/-0.02 Hz vs. 0.14+/-0.01 Hz). SEJP amplitude was abolished by bath applications of suramin (30 microM) or alpha,beta-meATP (30 microM). However, tetrodotoxin (TTX; 1 microM) and prazosin (0.1 microM) had no effect on this spontaneous activity. Electrical-field stimulation (EFS; 0.1 ms, 20 V, 0.2 Hz) induced an enhanced excitatory junction potential (EJP) in SHR but not in WKY (16.0+/-0.6 mV vs. 12.2+/-0.5 mV) which was abolished by TTX (1 microM), suramin (30 microM) and alpha,beta-meATP (30 microM). The degree of inhibition of both SEJP and EJP produced by alpha,beta-meATP (0.3-30 microM) was greater in SHR than in WKY. This study demonstrates an altered purinergic contribution to the co-transmission process in the prostatic portion of vas deferens from SHR.