Reserpine-induced postjunctional supersensitivity in rat vas deferens and caudal artery without changes in alpha adrenergic receptors.
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.
Nasseri
A
A
Barakeh
J F
JF
Abel
P W
PW
Minneman
K P
KP
D000818:Animals; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D010627:Phenethylamines / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D012110:Reserpine / Q000494:pharmacology*; D013623:Tail / Q000098:blood supply; D044024:Tetralones; D014649:Vas Deferens / Q000187:drug effects; D015016:Yohimbine / Q000378:metabolism
D010627:Phenethylamines; D011942:Receptors, Adrenergic, alpha; D044024:Tetralones; D010656:Phenylephrine; D015016:Yohimbine; C010652:BE 2254; D012110:Reserpine