ROLE OF SULFHYDRYL-GROUPS IN CONTRACTION OF VASCULAR SMOOTH-MUSCLE

  • 1 January 1979
    • journal article
    • research article
    • Vol. 208  (2) , 335-340
Abstract
While high concentrations (50 .mu.mol/l) of mercurial sulfhydryl (SH) reagents p-chloromercuribenzoate (PCMB) and p-chloromercuriphenyl sulfate (PCMPS) caused a nonspecific inhibition of constrictor responses in isolated rabbit ear arteries, lower concentrations had selective effects. At a concentration of 10 .mu.mol/l, both agents abolished responses to epinephrine and reduced responses to Ba and Ca, but responses to caffeine were unaffected by PCMB and potentiated by PCMPS. Responses to histamine were affected little by PCMPS, but with PCMB, histamine responses were first reduced but later potentiated. Ethacrynic acid, a nonmercurial SH inhibitor which enters the intracellular space, showed no specificity of action and inhibited contractile responses to all these agonists. SH inhibitors whose actions are limited to the cell membrane exert specific and nonspecific effects. The specific effect may be at SH groups associated with .alpha.-adrenoceptors while nonspecific effects may involve changes in membrane permeability.

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