Xiao-Ping Yang and Shigetoshi Chiba*
Department of Pharmacology, Shinshu University School of Medicine, Matsumoto
390-8621, Japan
*Corresponding author.ﾊﾊFAX:+81-263-37-3085
E-mail: Chiba@sch.md.Shinshu-u.ac.jp
Abstract: The periarterial electrical nerve stimulation at a frequency
of 4ﾊHz (30-s trains of pulses) induced a double-peaked vasoconstriction
in the canine splenic artery. The treatment with chloroethylclonidine (CEC,
60ﾊmM) markedly inhibited the second-peaked constriction,
whereas it produced an insignificant effect on the first-peaked response.
The vasoconstriction to noradrenaline (NA, 1ﾊnmol) was not significantly
influenced by 60ﾊmM CEC. On the other hand, WBﾊ4101
(1ﾊmM) consistently abolished the vascular response
induced by NA (1ﾊ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
Copyrightｩ The Japanese Pharmacological Society 2000
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