AJP - Heart and Circulatory Physiology, Vol 268, Issue 6 2358-H2365, Copyright © 1995 by American Physiological Society

ARTICLES

A fast transient outward current in cultured cells from human pulmonary artery smooth muscle

A. F. James, T. Okada and M. Horie
International Research Laboratories, Ciba-Geigy, Takarazuka, Japan.

A voltage-dependent transient outward current (I(to)) was observed in cells cultured from human pulmonary artery smooth muscle when K+, but not Cs+, was the dominant cation in the pipette solution. In 30% of cells investigated using the Cs+ pipette solution, a tetrodotoxin-sensitive inward current (I(in)) dependent on extracellular Na+ was evoked from depolarizations positive to -30 mV.Iin showed voltage-dependent inactivation with a membrane potential at 50% of the evoked current (V50%) of -75.53 +/- 0.81 mV and slope factor potential (Vs) of -10.73 +/- 0.01 mV. In the presence of 1 microM tetrodotoxin, I(to) was rapidly evoked by depolarizations positive to -40 mV and decayed with a single exponential time course (tau = 9.9 +/- 1.1 ms, pulse potential = +50 mV). I(to) also showed voltage-dependent inactivation with a V50% of -70.9 +/- 2.63 mV and Vs of -7.7 +/- 0.03 mV. I(to) was inhibited concentration dependently by the K+ channel blocker, 4-aminopyridine (4-AP), with a concentration of 4-AP at which I(to) was reduced to 50% of control of 36.5 +/- 2.8 microM. These cells possess voltage-dependent currents characteristic of the K(+)-selective fast transient outward and Na(+)-selective inward currents of smooth muscle cells.

This article has been cited by other articles:

				S. Zhang, H. Dong, L. J. Rubin, and J. X.-J. Yuan Upregulation of Na+/Ca2+ exchanger contributes to the enhanced Ca2+ entry in pulmonary artery smooth muscle cells from patients with idiopathic pulmonary arterial hypertension Am J Physiol Cell Physiol, June 1, 2007; 292(6): C2297 - C2305. [Abstract] [Full Text] [PDF]

				N. L. Jernigan and H. A. Drummond Vascular ENaC proteins are required for renal myogenic constriction Am J Physiol Renal Physiol, October 1, 2005; 289(4): F891 - F901. [Abstract] [Full Text] [PDF]

				R. Berra-Romani, M. P. Blaustein, and D. R. Matteson TTX-sensitive voltage-gated Na+ channels are expressed in mesenteric artery smooth muscle cells Am J Physiol Heart Circ Physiol, July 1, 2005; 289(1): H137 - H145. [Abstract] [Full Text] [PDF]

				A. Yaghi, S. Mehta, and D. G. McCormack Delayed rectifier potassium channels contribute to the depressed pulmonary artery contractility in pneumonia J Appl Physiol, September 1, 2002; 93(3): 957 - 965. [Abstract] [Full Text] [PDF]

				L. A. Shimoda, J. T. Sylvester, G. M. Booth, T. H. Shimoda, S. Meeker, B. J. Undem, and J. S. K. Sham Inhibition of voltage-gated K+ currents by endothelin-1 in human pulmonary arterial myocytes Am J Physiol Lung Cell Mol Physiol, November 1, 2001; 281(5): L1115 - L1122. [Abstract] [Full Text] [PDF]

				G. Boccara, C. Choby, J. M. Frapier, J. F. Quignard, J. Nargeot, G. Dayanithi, and S. Richard Regulation of Ca2+ Homeostasis by Atypical Na+ Currents in Cultured Human Coronary Myocytes Circ. Res., October 1, 1999; 85(7): 606 - 613. [Abstract] [Full Text] [PDF]

				L. A. Shimoda, J. T. Sylvester, and J. S. K. Sham Inhibition of voltage-gated K+ current in rat intrapulmonary arterial myocytes by endothelin-1 Am J Physiol Lung Cell Mol Physiol, May 1, 1998; 274(5): L842 - L853. [Abstract] [Full Text] [PDF]