Reserpine-induced postjunctional supersensitivity in rat vas deferens and caudal artery without changes in alpha adrenergic receptors

J Pharmacol Exp Ther. 1985 Aug;234(2):350-7.

Abstract

Caudal artery and vas deferens from rats treated chronically with reserpine (1 mg/kg/day i.p.) were used to study drug-induced postjunctional supersensitivity in smooth muscle. There was no change in contractile sensitivity of the rat vas deferens after 1 day of reserpine treatment; however, there were similar increases in sensitivity 4 and 7 days after reserpine treatment. The potencies of phenylephrine, methacholine and potassium chloride in causing contraction of the vas deferens were significantly increased by 4.9-, 19.5- and 1.23-fold, respectively, after 7 days of chronic treatment. This treatment also increased the potencies of phenylephrine, serotonin and potassium chloride in causing contraction of rat caudal artery by 1.8-, 1.7- and 1.23-fold, respectively; however, the potency of clonidine was unchanged after 7 days of reserpine treatment. There was no change in sensitivity to phenylephrine 1 day after reserpine treatment but sensitivity was significantly increased after 4 days. There was no significant change in maximum contractile response in either tissue to any of these agents after chronic reserpine treatment. Scatchard analysis of saturation isotherms of specific [125I]BE 2254 binding to membrane fractions from rat vas deferens and caudal artery showed no change in the density or affinity of alpha-1 adrenergic receptors after 1, 4 or 7 days of chronic reserpine treatment. In addition, no change was observed in specific [3H]rauwolscine binding to either tissue after 7 days of chronic reserpine treatment, suggesting no change in alpha-2 adrenergic receptors. These data indicate that changes in alpha adrenergic receptors are not involved in postjunctional supersensitivity of smooth muscle caused by chronic reserpine treatment.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • In Vitro Techniques
  • Male
  • Muscle Contraction / drug effects
  • Muscle, Smooth / drug effects*
  • Muscle, Smooth, Vascular / drug effects
  • Phenethylamines / metabolism
  • Phenylephrine / pharmacology
  • Rats
  • Rats, Inbred Strains
  • Receptors, Adrenergic, alpha / drug effects*
  • Reserpine / pharmacology*
  • Tail / blood supply
  • Tetralones*
  • Vas Deferens / drug effects
  • Yohimbine / metabolism

Substances

  • Phenethylamines
  • Receptors, Adrenergic, alpha
  • Tetralones
  • Phenylephrine
  • Yohimbine
  • BE 2254
  • Reserpine