Calcium-dependent chloride current activated by hyposmotic stress in rat lacrimal acinar cells
Tóm tắt
We have identified a whole-cell Cl− current activated by hyposmotic stress in rat lacrimal acinar cells using the patch-clamp technique. Superfusion of isolated single cells with hyposmotic solution (80% of control osmolarity) caused a gradual increase of the current, which was reversed on return to the control solution. The current-voltage relationship showed outward rectification, and the current showed time and voltage dependence: slowly activated by depolarizing voltages and rapidly inactivated by hyperpolarizing voltages. The increase in current was not observed when intracellular Ca2+ was chelated with EGTA. It was also inhibited by the absence of extracellular Ca2+, or the presence of gadolinium ions (20 μm Gd3+). We conclude that in rat lacrimal acinar cells hyposmotic stress activates Ca2+-dependent Cl− channels as a result of Ca2+ influx through a Gd3+-sensitive pathway. The Cl− channels involved appear to be indistinguishable from those activated by muscarinic stimulation. The inhibitory effect of Gd3+ suggests that stretch-activated nonselective cation channels may be responsible for the Ca2+ influx.
Tài liệu tham khảo
Banderali, U., Roy, G. 1992. Activation of K+ and Cl− channels in MDCK cells during volume regulation in hypotonic media. J. Membrane Biol. 126:219–234
Bear, C.E. 1990. A nonselective cation channel in rat liver cells is activated by membrane stretch. Am. J. Physiol. 258:C421-C428
Christensen, O. 1987. Mediation of cell volume regulation by Ca2+ influx through stretch-activated channels. Nature 330:66–68
Doroshenko, P., Neher, E, 1992. Volume-sensitive chloride conductance in bovine chromaffin cell membrane. J. Physiol. 449:197–218
Evans, M.G., Marty, A. 1986. Calcium-dependent chloride currents in isolated cells from rat lacrimal glands. J. Physiol. 378:437–460
Filipovic, D., Sackin, H. 1991. A calcium-permeable stretch-activated cation channel in renal proximal tubule. Am. J. Physiol. 260:F119-F129
Findlay, I. 1984. A patch-clamp study of potassium channels and whole-cell currents in acinar cells of the mouse lacrimal gland. J. Physiol. 350:179–195
Findlay, I., Petersen, O.H. 1985. Acetylcholine stimulates a Ca2+-dependent Cl− conductance in mouse lacrimal acinar cells. Pfluegers Arch. 403:328–330
Foskett, J.K. 1990. [Ca2+]i modulation of Cl− content controls cell volume in single salivary acinar cells during fluid secretion. Am. J. Physiol. 259:C998-C1004
Foskett, J.K., Melvin, J.E. 1989. Activation of salivary secretion: coupling of cell volume and [Ca2+]i in single cells. Science 244:1582–1585
Hamill, O.P., Marty, A., Neher, E., Sakmann, B., Sigworth, F.J. 1981. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pfluegers Arch. 391:85–100
Hazama, A., Okada, Y. 1988. Ca2+ sensitivity of volume-regulatory K+ and Cl− channels in cultured human epithelial cells. J. Physiol. 402:687–702
Hazama, A., Okada, Y. 1990. Biphasic rises in cytosolic free Ca2+ in association with activation of K+ and Cl− conductance during the regulatory volume decrease in cultured human epithelial cells. Pfluegers Arch. 416:710–714
Hoffmann, E.K., Simonsen, L.O. 1989. Membrane mechanisms in volume and pH regulation in vertebrate cells. Physiol. Rev. 69:315–382
Kanagasuntheram, P., Randle, P.J. 1976. Calcium metabolism and amylase release in rat parotid acinar cells. Biochem. J. 160:547–564
Kotera, T., Brown, P.D., Case, R.M. 1992. Hyposmotic stress activates calcium-dependent chloride channels in isolated rat lacrimal acinar cells. Physiologist (APS Conference Abstract Issue) 35:A-2
Kubo, M., Okada, Y. 1992. Arachidonic acid inhibits volume-sensitive Cl− currents in a human intestinal epithelial cell line. J. Physiol. 446:105P
Marty, A., Tan, Y.P., Trautmann, A. 1984. Three types of calcium-dependent channel in rat lacrimal glands. J. Physiol. 357:293–325
McCarty, N.A., O'Neil, R.G. 1991. Calcium-dependent control of volume regulation in renal proximal tubule cells: I. Swelling-activated Ca2+ entry and release. J. Membrane Biol. 123:149–160
Montrose-Rafizadeh, C., Guggino, W.B. 1991. Role of intracellular calcium in volume regulation by rabbit medullary thick ascending limb cells. Am. J. Physiol. 260:F402-F409
Pierce, S.K., Politis, A.D. 1990. Ca2+-activated cell volume recovery mechanisms. Annu. Rev. Physiol. 52:27–42
Rothstein, A., Mack, E. 1990. Volume-activated K+ and Cl− pathways of dissociated epithelial cells (MDCK): role of Ca2+. Am. J. Physiol. 258:C827-C834
Sarkadi, B., Parker, J.C. 1991. Activation of ion transport pathways by changes in cell volume. Biochim. Biophys. Acta 1071:407–427
Sole, C.K., Wine, J.J. 1991. Swelling-induced and depolarization-induced Cl− channels in normal and cystic fibrosis epithelial cells. Am. J. Physiol. 261:C658-C674
Suzuki, M., Kawahara, K., Ogawa, A., Morita, T., Kawaguchi, Y., Kurihara, S., Sakai, O. 1990. [Ca2+]i rises via G protein during regulatory volume decrease in rabbit proximal tubule cells. Am. J. Physiol. 258:F690-F696
Trautmann, A., Marty, A. 1984. Activation of Ca-dependent K channels by carbamoylcholine in rat lacrimal glands. Proc. Natl. Acad. Sci. USA 81:611–615
Valverde, M.A., Díaz, M., Sepúlveda, F.V., Gill, D.R., Hyde, S.C., Higgins, C.F. 1992. Volume-regulated chloride channels associated with the human multidrug-resistance P-glycoprotein. Nature 355:830–833
Weiss, H., Lang, F. 1992. Ion channels activated by swelling of Madin Darby Canine Kidney (MDCK) cells. J. Membrane Biol. 126:109–114
Worrell, R.T., Butt, A.G., Cliff, W.H., Frizzell, R.A. 1989. A volume-sensitive chloride conductance in human colonic cell line T84. Am. J. Physiol. 256:C1111-C1119
Yang, X.C., Sachs, F. 1989. Block of stretch-activated ion channels in Xenopus oocytes by gadolinium and calcium ions. Science 243:1068–1071