EFFECT OF HYDRALAZINE ON TENSION AND MEMBRANE-POTENTIAL IN THE RAT CAUDAL ARTERY

  • 1 January 1983
    • journal article
    • research article
    • Vol. 227  (2) , 322-326
Abstract
To determine whether the antihypertensive vasodilator, hydralazine (HYD), produces hyperpolarization of vascular muscle cells, the effect of HYD on membrane potential and contractile responses to phenylephrine and K+ was measured. HYD (1 .mu.M) caused a 4 mV hyperpolarization of phenylephrine-depolarized arteries (compared with controls without HYD), which could possibly account for up to 3/4 of the 39% decrease in tension measured. K+-contracted vessels were also 34% relaxed by 1 .mu.M HYD without an effect on membrane potential. HYD further relaxed phenylephrine-stimulated vessels previously relaxed by D-600 [methoxyverapamil], suggesting that Ca2+ channel blockade may not be an important mechanism of vasodilation for HYD. A nonmembrane action of HYD on arterial muscle probably multiplies the relaxant effect of membrane potential hyperpolarization. Both mechanisms would attenuate the effects of adrenergic stimulation.

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