On the abnormalities of contractile responses of rat vasa deferentia to norepinephrine in genetic hypertension.

Contractile responses to norepinephrine (NE) of strips of vasa deferentia from prostatic end isolated from rats with genetic hypertension and deoxycorticosterone (DOC)-salt induced hypertension were examined. Maximum responses to NE of vasa deferentia from all hypertensive and corresponding normotensive control rats were biphasic. Spontaneous rhythmic activities superimposed on the NE-induced contraction were observed in most of the SHR (spontaneously hypertensive rat) strips, some of the WKY (Wistar-Kyoto normotensive rat) strips and none of the NWR (regular normotensive Wistar rat) strips. Neither the fast- nor the slow-component of the maximum contractile response to NE was altered in the vasa deferentia from SHR compared to those from WKY and in vasa deferentia from DOC-salt hypertensive rats (DHR) compared to those from the corresponding DOC-salt treated but normotensive controls (DNR). However, the strips from NWR developed significantly greater tension than those from WKY and DNR. Our findings suggest that interpretation of studies on hypertension in rats should take into account differences between tissues related to the strain of the rats used as controls for genetic hypertension.