Abstract
Primary isolates of smooth muscle cells from the basilar artery of the rat were studied using whole-cell and single-channel patch-clamp techniques. Two distinct potassium currents were characterized. With low intracellular calcium, depolarization above 0 mV elicited an outward current of a few hundred pA (at +120 mV) with sigmoidal onset and little inactivation during 1.25 s steps. This current was reduced by bath application of 1 mM procaine or 1 mM strychnine, but not by 500 nM charybdotoxin. These are characteristics of the delayed rectifier potassium current in other preparations. With higher intracellular calcium, depolarization above 0 mV elicited a non-inactivating potassium current of several nA (at +120 mV). This current persisted in the presence of 1 mM procaine or strychnine but was reduced by bath application of 100 nM charybdotoxin. In whole-cell recordings in which intracellular calcium was unbuffered with EGTA, spontaneous transient outward currents were manifest and displayed voltage dependence and tail currents similar to the calcium-dependent current. The spontaneous transient current and the calcium-dependent current had similar sensitivity to charybdotoxin. Cell-free membrane patches contained one or more channels of 220 pS (in solutions symmetrical with respect to potassium) with similar voltage and calcium dependence. These are characteristics of the large conductance calcium-activated potassium current in other preparations.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Absher M, Woodcock-Mitchell J, Mitchell J, Baldor L, Low R, Warshaw D (1989) Characterization of vascular smooth muscle cell phenotype in long term culture. In Vitro Cell Dev Biol 25:183–192
Benham CD, Bolton TB (1986) Spontaneous transient outward currents in single visceral and vascular smooth muscle cells of the rabbit. J Physiol (Lond) 381:385–406
Benham CD, Bolton TB, Lang RJ, Takewaki T (1986) Calcium-activated potassium channels in single smooth muscle cells of rabbit jejunum and guinea-pig mesenteric artery. J Physiol (Lond) 371:45–67
Bolton TB, Lang RJ, Takewaki T, Benham CD (1985) Patch and whole-cell voltage clamp of single mammalian visceral and vascular smooth muscle cells. Experientia 41:887–894
Bonnet P, Rusch NJ, Harder DR (1991) Characteristics of an outward K+ current in freshly dispersed cerebral arterial muscle cells. Pflügers Arch 418:292–296
Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ (1981) Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflügers Arch 391:85–100
Harder DR (1980) Comparison of electrical properties of middle cerebral and mesenteric artery in cat. Am J Physiol 239:C23-C26
Harder DR, Dernbach P, Waters A (1987) Possible cellular mechanism for cerebral vasospasm after experimental subarachnoid hemorrhage in the dog. J Clin Invest 80:875–880
Hill CE, Hirst GDS, Silverberg GD, Van Helden DF (1986) Sympathetic innervation and excitability of arterioles originating from the rat middle cerebral artery. J Physiol (Lond) 371:305–316
Hirst GDS, Silverberg GD, Van Helden DF (1986) The action potential and underlying ionic currents in proximal rat middle cerebral arterioles. J Physiol (Lond) 371:289–304
Hodgkin AL, Huxley AF (1952) Currents carried by sodium and potassium ions through the membrane of the giant axon of Loligo. J Physiol (Lond) 116:449–472
Hodgkin AL, Rushton WAH (1946) The electrical constants of a crustacean nerve fibre. Proc R Soc Lond [B] 133:444–479
Jack JJB, Noble D, Tsien RW (1975) Electric current flow in excitable cells. Clarendon Press, Oxford, p 72
Katusic ZS, Shepherd JT (1988) Endothelium-dependent responses of cerebral arteries. In: Vanhoutte PM (ed) Relaxing and contracting factors. Humana Press, Clifton, N.J. pp 333–345
Miller C, Moczydlowski E, Latorre R, Phillips M (1985) Charybdotoxin, a protein inhibitor of single Ca2+-activated K+ channels from mammalian skeletal muscle. Nature 313:316–318
Mulvaney MJ (1986) Vascular smooth muscle; structure and function. In: Magro A et al. (eds) Central and peripheral mechanisms of cerebrovascular regulation. Plenum, New York, pp 83–110
Ohya Y, Kitamura K, Kuriyama H (1987) Cellular calcium regulates outward currents in rabbit intestinal smooth muscle. Am J Physiol 252:C401-C410
Sadoshima J-I, Akaike N, Tomoike H, Kanaide H, Nakamura M (1989) Voltage-dependent anion-selective channels in cultured smooth muscle cells of the rat aorta. Comp Biochem Physiol [92A]:61–63
Steele JA, Stockbridge N, Maljkovic G, Weir B (1991) Free radicals mediate actions of oxyhemoglobin on cerebrovascular smooth muscle cells. Circ Res 68:416–423
Toda N, Shimizu K, Ohta T (1980) Mechanism of cerebral arterial contraction induced by blood constituents. J Neurosurg 53:312–322
Tomita T (1969) The longitudinal tissue impedance of the smooth muscle of guinea-pig taenia coli. J Physiol (Lond) 201:145–159
Tomita T (1988) Ionic channels in smooth muscle studied with patch-clamp methods. J J Physiol 38:1–18
Toro L, Golzáles-Robles A, Stefani E (1986) Electrical properties and morphology of single vascular smooth muscle cells in culture. Am J Physiol 251:C763-C773
Waters A, Harder DR (1985) Altered membrane properties of cerebral vascular smooth muscle following subarachnoid hemorrhage: an electrophysiological study. I. Changes in resting membrane potential (Em) and effect on the electrogenic pump potential contributing to Em. Stroke 16:990–997
Zervas NT, Liszczak TM, Mayberg MR, Black PMcL (1982) Cerebrospinal fluid may nourish cerebral vessels through pathways in the adventitia that may be analogous to systemic vasa vasorum. J Neurosurg 56:475–481
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Stockbridge, N., Zhang, H. & Weir, B. Potassium currents of rat basilar artery smooth muscle cells. Pflügers Arch 421, 37–42 (1992). https://doi.org/10.1007/BF00374731
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00374731