Abstract
The effects of neuropeptide Y (NPY) on the Ca2+-activated K+ channel in smooth muscle cells from the rat tail artery were studied by whole-cell and single-channel patch-clamp recording techniques. In the presence of nifedipine (1 μM), whole-cell outward currents through Ca2+-activated K+ channels were inhibited by NPY in a dose-dependent manner from 20 to 200 nM. A maximum inhibition to about 48% of the control current could be achieved. Recordings from outside-out patches showed that the open probability of Ca2+-activated K+ channels were similarly inhibited by NPY. At 200 nM NPY, the open probability was reduced to about 36% of the control value. NPY did not affect the open times or current amplitude, but increased significantly the short (from 0.49 to 0.58 ms) and long (from 441 to 728 ms) closed times. Inhibition of Ca2+-activated K+ channels by NPY may contribute to its excitatory action on vascular smooth muscle cells.
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Beech DJ, Bolton TB (1989) Two components of potassium current activated by depolarization of single smooth muscle cells from the rabbit portal vein. J Physiol (Lond) 418:293–309
Bolzon BJ, Cheung DW (1989) Isolation and characterization of single vascular smooth muscle cells from spontaneously hypertensive rats. Hypertension 14:137–144
Bolzon BJ, Xiong Z, Cheung DW (1993) Membrane rectification in single smooth muscle cells from the rat tail artery. Pflügers Arch 425:482–490
Brayden JE, Nelson MT (1992) Regulation of arterial tone by activation of calcium-dependent potassium channels. Science 256:532–535
Cheung DW (1982) Two components in the cellular response of rat tail arteries to nerve stimulation. J Physiol (Lond) 328:461–468
Cheung DW (1984) Neural regulation of electrical and mechanical activites of the rat tail artery. Pflügers Arch 400:335–337
Cheung DW (1991) Neuropeptide Y potentiates specifically the purinergic component of the neural responses in the guinea pig saphenous artery. Circ Res 68:1401–1407
Cheung DW, MacKay MJ (1986) The effects of Bay K 8644 and nifedipine on the neural responses of the rabbit ear artery. Br J Pharmacol 88:363–368
Fabiato A (1988) Computer programs for calculating total from specified free or free from specified total ionic concentrations in aqueous solutions containing multiple metals and ligands. Methods Enzymol 157:378–417
Gola M, Crest M (1993) Colocalization of active KCa channels and Ca2+ channels within Ca2+ domains in helix neurons. Neuron 10:689–699
Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ (1981) Improved pathc-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflügers Arch 391:85–100
Lundberg JM, Pernow J, Lacroix JS (1989) Neuropeptide Y: sympathetic cotransmitter and modulator? News Physiol Sci 4:13–17
Pernow J, Saria A, Lundberg JM (1986) Mechanisms underlying pre- and postjunctional effects of neuropeptide Y in sympathetic vascular control. Acta Physiol Scand 126:239–249
Robitaille R, Garcia ML, Kaczorowski GJ, Charlton MP (1993) Functional colocalization of calcium and calcium-gated potassium channels in control of transmitter release. Neuron 11:645–655
Small DL, Bolzon BJ, Cheung DW (1992) Endothelium-independent potentiating effects of neuropeptide Y in the rat tail artery. Eur J Pharmacol 210:131–136
Twitchell WA, Rane SG (1993) Opioid peptide modulation of Ca2+-dependent K+ and voltage-activated Ca2+ currents in bovine adrenal chromaffin cells. Neuron 10:701–709
White RE, Schonbrunn A, Armnstrong DL (1991) Somatostatin stimulates Ca2+ through protein dephosphorylation. Nature 351:570–573
Xiong Z, Bolzon BJ, Cheung DW (1993) Neuropeptide Y potentiates calcium-channel currents in single vascular smooth muscle cells. Pflügers Arch 423:504–510
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Xiong, Z., Cheung, D.W. Neuropeptide Y inhibits Ca2+-activated K+ channels in vascular smooth muscle cells from the rat tail artery. Pflugers Arch. 429, 280–284 (1994). https://doi.org/10.1007/BF00374324
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DOI: https://doi.org/10.1007/BF00374324