AJP - Cell Physiology, Vol 267, Issue 4 C1080-C1086, Copyright © 1994 by American Physiological Society

ARTICLES

Large Ca(2+)-activated K+ channels responsive to angiotensin II in cultured human mesangial cells

J. D. Stockand and S. C. Sansom
Department of Medicine, University of Texas Health Science Center at Houston 77225.

The patch-clamp method was used to determine the properties and response to angiotensin II (ANG II) of K+ channels in subpassages of human mesangial cell cultures. In cell-attached patches, with 140 mM KCl in the bath and cell potential equal to 40 mV, the open probability (Po) of large K+ channels (MKCa) was 0.8 with 0.5 mM Ca2+ in the bath and < 0.05 if the bath Ca2+ concentration was reduced to 1.0 microM. Open and closed dwell-time histograms of MKCa displayed both fast and slow time constants. Addition of ANG II (100 nM) to the bath solution (Ca2+ = 1.0 microM) increased the Po of MKCa in cyclic bursts by decreasing the time constant of the slow closed state. In excised inside-out patches, the mean single-channel conductance of MKCa was 206 pS in symmetrical 140 mM KCl. The selectivity sequence, established in asymmetrical cationic solutions, was K+ (1.0) > Rb+ (0.54) > NH+4 (0.11) > > Cs+ = Na+ (< 0.05). The Po of MKCa was increased by depolarizing potentials and high bath Ca2+. The Boltzmann distribution was consistent with an effective valence of 1.0, and the Hill coefficient for Ca2+ activation was 0.52. We conclude that MKCa has properties similar to large Ca(2+)-activated K+ channels and may act to repolarize the membrane of mesangial cells in response to an agonist-induced mobilization of intracellular Ca2+.

This article has been cited by other articles:

				X. Wang, J. L. Pluznick, D. C. Settles, and S. C. Sansom Association of VASP with TRPC4 in PKG-mediated inhibition of the store-operated calcium response in mesangial cells Am J Physiol Renal Physiol, December 1, 2007; 293(6): F1768 - F1776. [Abstract] [Full Text] [PDF]

				L. Magnusson, C. M. Sorensen, T. H. Braunstein, N.-H. Holstein-Rathlou, and M. Salomonsson Renovascular BKCa channels are not activated in vivo under resting conditions and during agonist stimulation Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2007; 292(1): R345 - R353. [Abstract] [Full Text] [PDF]

				J. L. Pluznick and S. C. Sansom BK channels in the kidney: role in K+ secretion and localization of molecular components Am J Physiol Renal Physiol, September 1, 2006; 291(3): F517 - F529. [Abstract] [Full Text] [PDF]

				R. Ma, J. L. Pluznick, and S. C. Sansom Ion Channels in Mesangial Cells: Function, Malfunction, or Fiction Physiology, April 1, 2005; 20(2): 102 - 111. [Abstract] [Full Text] [PDF]

				T. L. Pallone, C. Cao, and Z. Zhang Inhibition of K+ conductance in descending vasa recta pericytes by ANG II Am J Physiol Renal Physiol, December 1, 2004; 287(6): F1213 - F1222. [Abstract] [Full Text] [PDF]

				P. E. Kudlacek, J. L. Pluznick, R. Ma, B. Padanilam, and S. C. Sansom Role of h{beta}1 in activation of human mesangial BK channels by cGMP kinase Am J Physiol Renal Physiol, August 1, 2003; 285(2): F289 - F294. [Abstract] [Full Text] [PDF]

				R. W. Fallet, J. P. Bast, K. Fujiwara, N. Ishii, S. C. Sansom, and P. K. Carmines Influence of Ca2+-activated K+ channels on rat renal arteriolar responses to depolarizing agonists Am J Physiol Renal Physiol, April 1, 2001; 280(4): F583 - F591. [Abstract] [Full Text] [PDF]

				K. E. PURDY and W. J. ARENDSHORST Iloprost Inhibits Inositol-1,4,5-Trisphosphate-Mediated Calcium Mobilization Stimulated by Angiotensin II in Cultured Preglomerular Vascular Smooth Muscle Cells J. Am. Soc. Nephrol., January 1, 2001; 12(1): 19 - 28. [Abstract] [Full Text]

				R. MA and S. C. SANSOM Epidermal Growth Factor Activates Store-Operated Calcium Channels in Human Glomerular Mesangial Cells J. Am. Soc. Nephrol., January 1, 2001; 12(1): 47 - 53. [Abstract] [Full Text]

				S. C. Sansom, R. Ma, P. K. Carmines, and D. A. Hall Regulation of Ca2+-activated K+ channels by multifunctional Ca2+/calmodulin-dependent protein kinase Am J Physiol Renal Physiol, August 1, 2000; 279(2): F283 - F288. [Abstract] [Full Text] [PDF]

				R. Ma, S. Smith, A. Child, P. K. Carmines, and S. C. Sansom Store-operated Ca2+ channels in human glomerular mesangial cells Am J Physiol Renal Physiol, June 1, 2000; 278(6): F954 - F961. [Abstract] [Full Text] [PDF]

				D. A. Hall, P. K. Carmines, and S. C. Sansom Dihydropyridine-sensitive Ca2+ channels in human glomerular mesangial cells Am J Physiol Renal Physiol, January 1, 2000; 278(1): F97 - F103. [Abstract] [Full Text] [PDF]

				J. D. STOCKAND and S. C. SANSOM Glomerular Mesangial Cells: Electrophysiology and Regulation of Contraction Physiol Rev, July 1, 1998; 78(3): 723 - 744. [Abstract] [Full Text] [PDF]

				J. D. Stockand, M. Silverman, D. Hall, T. Derr, B. Kubacak, and S. C. Sansom Arachidonic acid potentiates the feedback response of mesangial BKCa channels to angiotensin II Am J Physiol Renal Physiol, April 1, 1998; 274(4): F658 - F664. [Abstract] [Full Text] [PDF]

				T. Morita, K. Hanaoka, M. M. Morales, C. Montrose-Rafizadeh, and W. B. Guggino Cloning and characterization of maxi K+ channel alpha -subunit in rabbit kidney Am J Physiol Renal Physiol, October 1, 1997; 273(4): F615 - F624. [Abstract] [Full Text] [PDF]

				S. C. Sansom, J. D. Stockand, D. Hall, and B. Williams Regulation of Large Calcium-activated Potassium Channels by Protein Phosphatase 2A J. Biol. Chem., April 11, 1997; 272(15): 9902 - 9906. [Abstract] [Full Text] [PDF]

				T. L. Pallone and J. M.-C. Huang Control of descending vasa recta pericyte membrane potential by angiotensin II Am J Physiol Renal Physiol, June 1, 2002; 282(6): F1064 - F1074. [Abstract] [Full Text] [PDF]