Tohoku J. Exp. Med., 2002, 196 (3)

Different Sensitivities to a₁ Adrenoceptor Blockade on Periarterial Sympathetic Nerve-Induced Constriction by Low and High
Frequencies in Canine Isolated Splenic Arteries

XIAO-PING YANG and SHIGETOSHI CHIBA

Department of Pharmacology, Shinshu University School of Medicine, Matsumoto 390-8621

The periarterial nerve electrical stimulation at 4 and 10 Hz induced a monophasic vasoconstriction of the canine splenic artery in a pulse number-related manner (1-30 pulses). The responses at 4 Hz were not significantly affected by 0.1 mM prazosin, but abolished by 1 mM a, b-methylene ATP. Prazosin (0.1 mM) partially but significantly inhibited responses at 10 Hz, and the remaining responses were blocked by 1 mM a, b-methylene ATP. It indicates that the monophasic vasoconstrictor response to short pulses of stimulation at a low frequency is mediated by P2X-receptors, whereas the response at a high frequency may be due to activation of not only P2X-receptors but also a₁ adrenoceptors.

Keywords —— dog splenic artery; sympathetic nerve electrical stimulation; P2X-purinoceptor; a₁-adrenoceptor

© 2002 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2002, 196, 151-155

Address for reprints: Shigetoshi Chiba, Department of Pharmacology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan.

e-mail: Chiba@sch.md.shinshu-u.ac.jp