Inhibition of Vasoconstriction and Ca^<2+> Currents Mediated by Neuropeptide Y Y2 Receptors

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The effects of neuropeptide Y(NPY)and agonists selective for NPY Y1 and Y2 receptors were studied on contraction and Ca^<2+> currents in arterial smooth muscle. In isolated arterioles from the guinea-pig small intestine, small brief constrictions were evoked by depolarising the arteriolar smooth muscle using high K^+ solution applied from a micropipette. The constrictions were reduced in amplitude by the Y2-selective agonists PYY(13-36)and N-acetyl[Leu^<28>, Leu^<31>]NPY-(24-36)in concentrations from 20-100 nM. NPY or the Y1-selective agonist[Leu31 Pro34]NPY in concentrations from 50 pM to 100 nM increased the amplitude of the constrictions, with a maximum effect at 10 nM. Smooth muscle cells were isolated from rat small mesenteric arteries, and voltage-activated Ca^<2+> currents measured by whole cell patch clamping. The peak amplitude of the Ca^<2+> currents was decreased by N-acetyl[Leu^<28>, Leu^<31>]NPY-(24-36), and by NPY(100nM). [Leu^<31>, Pro^<34>]NPY either had no effect or slightly increased the Ca^<2+> currents. We conclude that Y2 receptors on vascular smooth muscle can reduce Ca^<2+> currents induced by depolarisation, and thus oppose constriction caused by smooth muscle depolarization.
日本平滑筋学会の論文