XiaoﾐPing Yang and Shigetoshi Chiba*
Department of Pharmacology, Shinshu University School of Medicine, Matsumoto
390ﾐ8621, Japan
*To whom correspondence should be addressed.
Abstract: The periarterial electrical nerve stimulation readily
induced a doubleﾐpeaked vasoconstriction in the isolated, perfused canine
splenic artery. P2XﾐPurinoceptors have previously been shown to be involved
mainly in the 1stﾐphase response and alpha1ﾐadrenoceptors, mostly
in the 2ndﾐone. The dose used of neuropeptide
Y (NPY) (0.01-0.1 microM) given into the preparation caused a slight but
insignificant vasoconstriction. The treatﾐ
ment with NPY at concentrations of 0.01-0.1 microM produced a parallel inhibition
on the 1stﾐ and 2ndﾐphase responses following nerve stimulation at the frequencies
used (1-10 Hz) in a doseﾐdependent manner. The
vasoconstrictor responses to administered ATP (0.01-1 micromol) or noradrenaline
(0.03-3 nmol) were slightly but
not significantly potentiated by 0.1 microM NPY. The results indicate that
NPY predominantly exerts a prejunctionally inhibitory modulation on the
purinergic and adrenergic transmission in peripheral sympathetic nerves
innervating the canine splenic artery.
Keywords: Neuropeptide Y, Periarterial nerve stimulation, Sympathetic
cotransmission