Contractile responses of vasa deferentia from rats with genetic and experimental hypertension

The changes in hypertension of the characteristics of the contractile responses of the prostatic portion of the vasa deferentia to norepinephrine (NE), K+, Ca2+ and transmural field stimulation were investigated. Responses of strips from Wistar-Kyoto strain normotensive rats (WKY) were compared to those of strips from spontaneously hypertensive rats (SHR). Also strips from regular normotensive Wistar rats (NWR) which failed to develop hypertension after deoxycorticosterone (DOC)-salt treatment (DNR) were compared to those from NWR with DOC-salt induced hypertension (DHR). Cumulative dose-response curves to NE or KC1 were similar for strips from controls and hypertensive animals in both forms of hypertension. The relaxation of strips from NE contraction after drug washout followed a single exponential component and was slower for those from SHR than for the control but the relaxation rate of strips from DHR was not significantly different from that of the control strips. Relaxation of vasa deferentia from high K+-contraction displayed two exponential components. Significantly slower relaxation was found only in the second component in SHR compared to that in WKY. The relaxation rate was not different in either component of the relaxation response after washout of KC1 in vasa deferentia from DHR and DNR. The maximum contractile responses to NE, were unchanged in hypertension but differed between groups used to study genetic and experimental hypertension. The maximum contractile responses to NE were significantly higher in both DNR and DHR than in strips from either WKY or SHR. The contractile response of vasa deferentia to Ca2+ in potassium depolarized muscle was increased significantly at higher Ca2+ concentration in DHR compared to DNR.(ABSTRACT TRUNCATED AT 250 WORDS)