Abstract
A small conductance K+ channel was identified in smooth muscle cells of the rat aortic cell line A7r5 and also in rat aortic smooth muscle cells in primary culture, using conventional single-channel recording techniques. The single-channel conductance shows no rectification, either in the range −70 to +40 mV under asymmetrical conditions (9.1 pS), or in the range −100 to +50 mV in symmetrical 150 mM K+ (37 pS). Channel activity is reversibly inhibited by extracellular application of charybdotoxin, with a concentration of 8 nM producing half-maximal inhibition. It is unaffected by apamin or scyllatoxin. Channel activity depends on the presence of free Ca2+ on the cytosolic face of the membrane, with an activation zone between 0.1 and 1 μM. This small-conductance, charybdotoxin-sensitive, Ca2+-regulated K+ channel is activated by vasoconstrictors such as vasopressin and endothelin.
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References
Auguste P, Hugues M, Gravé B, Gesquière JC, Maes P, Tartar A, Romey G, Schweitz H, Lazdunski M (1990) Leiurotoxin I (Scyllatoxin) a peptide ligand for Ca2+-activated K+ channels. J Biol Chem 265:4753–4759
Barret JN, Magleby KL, Pallota BS (1982) Properties of single calcium-activated potassium channels in cultured rat muscle. J Physiol (Lond) 331:211–230
Benham CD, Bolton TB, Lang RJ, Takewaki T (1986) Calcium-activated potassium channels in single smooth muuscle cells of rabbit jejunum and guinea-pig mesenteric artery. J Physiol (Lond) 371:45–67
Bernardi H, Bidard J-N, Fosset M, Hugues M, Mourre C, Rehm H, Romey G, Schmid-Antomarchi H, Schweitz H, Weille de J, Lazdunski M (1989) Molecular properties of potassium channels. Arzneimittelforschung 39:159–163
Blatz AL, Magleby KL (1986) Single apamin-blocked Ca-activated K+ channels of small conductance in cultured rat skeletal muscle. Nature 323:718–720
Capiod T, Ogden DC (1989) The properties of calcium-activated potassium ion channels in guinea-pig isolated hepatocytes. J Physiol (Lond) 409:285–295
Castle NA, Strong PN (1986) Identification of two toxins from scorpion (Leiurus quinquestriatus) venom which block distinct classes of calcium-activated potassium channel. FEBS Lett 209:117–121
Castle NA, Haylett DG, Jenkinson DH (1989) Toxins in the characterization of potassium channels. Trends Neurosci 12:59–65
Chicchi GG, Gimenez-Gallego G, Ber E, Garcia ML, Winquist R, Cascieri MA (1988) Purification and characterization of a unique, potent inhibitor of apamin binding from Leiurus quinquestriatus hebraeus venom. J Biol Chem 263:10192–10197
Enomoto K-I, Furuya K, Maeno T, Edwards C, Oka T (1991) Oscillating activity of a calcium-activated K+ channel in normal and cancerous mammary cells in culture. J Membr Biol 119:133–139
Gauldie J, Hanson JM, Rumjanek FD, Shipolini RA, Vernon CA (1976) The peptide components of bee benom. Eur J Biochem 61:369–376
Gelband CH, Lodge NJ, Van Breemen C (1989) A Ca2+-activated K+ channel from rabbit aorta: modulation by cromakalim. Eur J Pharmacol 167:201–210
Giminez-Gallego G, Navia MA, Reuben JP, Katz GM, Kaczorowski GJ, Garcia ML (1988) Purification, sequence, and model structure of charybdotoxin, a potent selective inhibitor of calcium-activated potassium channels. Proc Natl Acad Sci USA 85:3329–3333
Inoue R, Okabe K, Kitamura K, Kuriama H (1986) A newly identified Ca2+ dependent K+-channel in the smooth muscle membrane of single cells dispersed from the rabbit portal vein. Pflügers Arch 406:138–143
Kolb HA (1990) Potassium channels in excitable and non-excitable cells. Rev Physiol Biochem Pharmacol 115:51–91
Lang DG, Ritchie AK (1990) Tetraethylammonium blockade of apamin-sensitive and insensitive Ca2+-activated K+ channels in a pituitary cell line. J Physiol (Lond) 425:117–132
Marty A (1981) Ca-dependent K channels with large unitary conductance in chromaffin cell membranes. Nature 291:497–500
Miller C, Moczydlowski E, Latorre R, Phillipps M (1985) Charybdotoxin, a protein inhibitor of single Ca2+-activated K+ channels from mammalian skeletal muscle. Nature 313:316–318
Pallotta BS, Magleby KL, Barrett JN (1981) Single channel recordings of Ca2+-activated K+ currents in rat muscle cell culture. Nature 293:471–474
Pennefather P, Lancaster B, Adam PR, Nicoll RA (1985) Two distinct Ca-dependent potassium currents in bullfrog sympathetic ganglion cells. Proc Natl Acad Sci USA 82:3040–3044
Reinhart PH, Chung S, Levitan IB (1989) A family of calcium-dependent potassium channels from rat brain. Neuron 2:1031–1041
Romey G, Lazdunski M (1984) The coexistence in rat muscle cells of two distinct classes of Ca2+-dependent K+ channels with different pharmacological properties and different physiological functions. Biochem Biophys Res Commun 118:669–674
Sands SB, Lewis RS, Cahalan MD (1989) Charybdotoxin blocks voltage-gated K+ channels in human and murine T lymphocytes. J Gen Physiol 93:1061–1074
Sauvé R, Simoneau C, Monette R, Roy G (1986) Single-channel analysis of the potassium permeability in HeLa cancer cells: evidence for a calcium-activated potassium channel of small unitary conductance. J Membr Biol 92:269–282
Sauvé R, Parent L, Simoneau C, Roy G (1988) External ATP triggers a biphasic activation process of a calcium-dependent K+ channel in cultured bovine aortic endothelial cells. Pflügers Arch 412:469–481
Schweitz H, Bidard J-N, Maes P, Lazdunski M (1989) Charybdotoxin is a new member of the K+ channel toxin family that includes dendrotoxin I and mast cell degranulating peptide. Biochemistry 28:9708–9714
Schweitz H, Stansfeld CE, Bidard J-N, Fagni L, Maes P, Lazdunski M (1989) Charybdotoxin blocks dendrotoxin-sensitive voltage-activated K+channels. FEBS Lett 250:519–522
Smith C, Phillips M, Miller C (1986) Purification of charybdotoxin, a specific inhibitor of the high-conductance Ca2+-activated K+ channel. J Biol Chem 261:14607–14613
Van Renterghem C, Romey G, Lazdunski M (1988) Vasopressin modulates the spontaneous electrical activity in aortic cells (A7r5) by acting on three different types of ionic channels. Proc Natl Acad Sci USA 85:9365–9369
Van Renterghem C, Vigne P, Barhanin J, Schmid-Alliana A, Frelin C, Lazdunski M (1988) Molecular mechanism of action of the vasoconstrictor peptide endothelin. Biochem Biophys Res Commun 157:977–985
Vigne P, Breittmayer J-P, Lazdunski M, Frelin C (1988) The regulation of the cytoplasmic free Ca concentration in aortic smooth muscle cells (A7r5 line) after stimulation by vasopressin and bombesin. Eur J Biochem 176:47–52
Williams DL, Katz GM, Roy-Constantin L, Reuben JP (1988) Guanosine 5′-monophosphate modulates gating of high-conductance Ca2+-activated K+ channels in vascular smooth muscle cells. Proc Natl Acad Sci USA 85:9360–9364
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Van Renterghem, C., Lazdunski, M. A small-conductance charybdotoxin-sensitive, apamin-resistant Ca2+-activated K+ channel in aortic smooth muscle cells (A7r5 line and primary culture). Pflugers Arch. 420, 417–423 (1992). https://doi.org/10.1007/BF00374614
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DOI: https://doi.org/10.1007/BF00374614