Jpn. J. Pharmacol. 84 (3), 360-362 (2000)

Periarterial Electrical Nerve Stimulation-Induced Adrenergic Vasoconstriction Inhibited by Adrenergic a1B-Receptor Blockade but Not by a1A-Blockade

Xiao-Ping Yang and Shigetoshi Chiba*

Department of Pharmacology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan
*Corresponding author.╩╩FAX:+81-263-37-3085

Abstract: The periarterial electrical nerve stimulation at a frequency of 4╩Hz (30-s trains of pulses) induced a double-peaked vasoconstriction in the canine splenic artery. The treatment with chloroethylclonidine (CEC, 60╩mM) markedly inhibited the second-peaked constriction, whereas it produced an insignificant effect on the first-peaked response. The vasoconstriction to noradrenaline (NA, 1╩nmol) was not significantly influenced by 60╩mM CEC. On the other hand, WB╩4101 (1╩mM) consistently abolished the vascular response induced by NA (1╩nmol), but rather potentiated the double-peaked constriction. The results indicate that neuronal NA may junctionally exert its vasoconstrictor effect via an activation of postjunctional a1B-receptors, whereas exogenous NA may extrajunctionally activate a1A-receptors for its vascular action in the canine splenic artery.

Keywords: a1-Adrenoceptor subtype, Adrenergic transmission, Chloroethylclonidine

Copyrightę The Japanese Pharmacological Society 2000

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