Effect of hydralazine on tension and membrane potential in the rat caudal artery

K. Hermsmeyer, A. Trapani, Peter W. Abel, M. Worcel

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Abstract

To determine whether the vasodilator, hydralazine (HYD), produces hyperpolarization of vascular muscle cells, we measured the effect of HYD on membrane potential and contractile responses to phenylephrine and K+. HYD (1 μM) caused a 4 mV hyperpolarization of phenylephrine-depolarized arteries (compared with controls without HYD), which could possibly account for up to three-fourths of the 39% decrease in tension measured. K+-contracted vessels were also 34% relaxed by 1 μM HYD without an effect on membrane potential. In addition, HYD further relaxed phenylephrine-stimulated vessels previously relaxed by D-600, suggesting that Ca++ channel blockade may not be an important mechanism of vasodilation for HYD. The evidence suggests that 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.

Original languageEnglish
Pages (from-to)322-326
Number of pages5
JournalJournal of Pharmacology and Experimental Therapeutics
Volume227
Issue number2
Publication statusPublished - 1983
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Pharmacology

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