Summary
A high-conductance K+-selective ion channel was studied in excised membrane patches from human G292 osteoblast-like osteosarcoma cells. Channel conductance averaged ∼170 pS in symmetric solutions of 153mm KCl, and ∼135 pS when the pipette was filled with standard saline (150mm NaCl). The probability of the channel being in an open state (P open) increased with membrane potential, internal calcium, and applied negative pressure. At pCa7, channel activity was observed at membrane potentials greater than ∼60 mV, while at pCa3, channel activity was seen at ∼10 mV. Likewise, in the absence of applied pressure, channel openings were rare (P open = 0.02), whereas with −3 cm Hg applied pressure,P open increased to ∼0.40. In each case, i.e., voltage, calcium concentration, and pressure, the increase inP open resulted from a decrease in the duration of long-closed (interburst) intervals and an increase in the duration of long-open (burst) intervals. Whole-cell responses were consistent with these findings. Hypotonic shock produced an increase in the amplitude and conductance of the outward macroscopic current and a decrease in its rise time, and both single-channel and whole-cell currents were blocked by barium. It is suggested that the voltage-gated, calcium dependent maxi-K+ channel in G292 osteoblastic cells is sensitive to membrane stretch and may be directly involved in osmoregulation of these cells. Further, stretch sensitivity o£ the maxi-K+ channel in osteotrophic cells may represent an adaptation to stresses associated with mechanical loading of mineralized tissues.
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Bolivar, J.J., Cereijido, M. 1987. Voltage and Ca2+-activated K+ channel in cultured epithelial cells (MDCK).J. Membrane Biol. 97:43–51
Chesnoy-Marchais, D., Fritsch, J. 1989. Chloride current activated by cyclic AMP and parathyroid hormone in rat osteoblasts.Pfluegers Arch. 415:104–114
Chow, S.Y., Chow, Y.C., Jee, W.S.S., Woodbury, D.M. 1984. Electrophysiological properties of osteoblastlike cells from the cortical endosteal surface of rabbit long bones.Calcif. Tissue Int. 36:401–408
Davidson, R.M., Tatakis, D.N., Auerbach, A. 1990. Multiple forms of mechanosensitive ion channels in osteoblast-like cells.Pfluegers Arch.,416:646–651
Dixon, S.J., Aubin, J.E., Dainty, J. 1984. Electrophysiology of a clonal osteoblast-like cell line: Evidence for the existence of a Ca2+-activated conductance.J. Membrane Biol. 80:49–58
Duncan, R., Misler, S. 1989: Voltage-activated and stretch-activated Ba2+ conducting channels in an osteoblast-like cell line (UMR 106).FEBS Lett. 251:17–21
Edelman, A., Fritsch, J., Balsan, S. 1986. Short-term effects of PTH on cultured rat osteoblasts: changes in membrane potential.Am. J. Physiol. 251:C483–490
Ferrier, J., Ward, A. 1986. Electrophysiological differences between bone cell clones: Membrane potential responses to parathyroid hormone and correlation with the cAMP response.J. Cell. Physiol. 126:237–242
Fritsch, J., Edelman, A., Balsan, S. 1988. Early effects of parathyroid hormone on membrane potential of rat osteoblasts in culture: Role of cAMP and Ca2+.J. Bone Mineral Res. 3:547–554
Gallin, E. 1984. Calcium- and voltage-activated potassium channels in human macrophages.Biophys. J. 46:821–825
Hamill, O.P., Marty, A., Neher, E., Sakmann, B., Sigworth, F. 1981. Improved patch-clamp techniques for high resolution current recording from cells and cell-free membrane patches.Pfluegers Arch. 391:85–100
Heath, J.C., Meikle, M.C., Atkinson, S.J., Reynolds, J.J. 1984a. A factor synthesized by rabbit periosteal fibroblasts stimulates bone resorption and collagenase production by connective tissue cell in vitro.Biochim. Biophys. Acta 800:301–305
Heath, J.C., Atkinson, S.J., Meikle, M.C., Reynolds, J.J. 1984b. Mouse osteoblasts synthesize collagenase in response to bone resorbing agents.Biochim. Biophys. Acta 802:151–154
Magleby, K.L., Pallotta, B.S. 1983a. Calcium dependence of open and shut intervals distributions from calcium-activated potassium channels in cultured rat muscle.J. Physiol. 344:585–604
Magleby, K.L., Pallotta, B.S. 1983b. Burst kinetics of single calcium-activated potassium channels in cultured rat muscle.J. Physiol. 344:605–623
Morris, C.E., Horn, R. 1991. Failure to elicit neuronal macroscopic mechanosensitive currents anticipated by single channel studies.Science 251:1246–1248
Ngan, P.W., Crock, B., Varghese, J., Lanese, R., Shanfield, J., Davidovitch, Z. 1988. Immunohistochemical assessment of the effect of chemical and mechanical stimuli on cAMP and prostaglandin E levels in human gingival fibroblasts in vitro.Arch. Oral Biol. 33:163–174
Peebles, P.T., Trisch, T., Papageorge, A.G. 1978. Isolation of four unusual pediatric solid tumor cell lines.Pediatric Res. 12:485(#727)
Pollack, S.R., Salzstein, R., Pienkowski, D. 1984. The electric double layer in bone and its influence on stress-generated potentials.Calcif. Tissue Int. 36:S77
Ravesloot, J.H., Van Houten, R.J., Ypey, D.L., Nijweide, P.J. 1990. Identification of Ca2+-activated K+ channels in cells of embryonic chick osteoblast cultures.J. Bone Mineral Res. 5:1201–1210
Ravesloot, J.H., Van Houten, R.J., Ypey, D.L., Nijweide, P.J. 1991. High-conductance anion channels in embryonic chick osteogenic cells.J. Bone Mineral Res. 6:355–364
Rodan, G. 1991. Perspectives: Mechanical loading, estrogen deficiency, and the coupling of bone formation to bone resorption.J. Bone Mineral Res. 6:527–530
Rodan, G.A., Burrette, C.A., Harvey, A., Mensi, T. 1975. Cyclic AMP and cyclic GMP: Mediators of the mechanical effects of bone remodeling.Science 189:467–469
Sackin, H. 1989. A stretch-activated K+ channel sensitive to cell volume.Proc. Natl. Acad. Sci. USA 86:1731–1735
Sandy, J.R., Farndale, R.W. 1991. Second messengers: regulators of mechanically-induced tissue remodeling.Eur. J. Orthodont. 13:271–278
Sandy, J.R., Meghji, S., Farndale, R.W., Meikle, M.C. 1989. Dual elevation of cyclic AMP and inositol phosphates in response to mechanical deformation of murine osteoblasts.Biochim. Biophys. Acta 1010:265–269
Shupnik, M.A., Tashjian, A.H., Jr. 1982. Epidermal growth factors and phorbol ester actions on human osteosarcoma cells: Characterization of responsive and nonresponsive cell lines.J. Biol. Chem. 257:12161–12164
Singer, J.J., Walsh, J.V. 1984. Large conductance Ca2+-activated K+ channels in smooth muscle cell membrane.Biophys. J. 45:68–70
Snowdowne, K.W. 1987. The effects of stretch on sarcoplasmic free calcium of frog skeletal muscle at rest.Biochim. Biophys. Acta 862:441–444
Taniguchi, J., Guggino, W.B. 1989. Membrane stretch: a physiological stimulator of Ca2+-activated K+ channels in thick ascending limb.Am. J. Physiol. 257:F347-F352
Ubl, J., Murer, H., Kolb, H.-A. 1988. Hypotonic shock evoked opening of Ca2+-activated K+ channels in opossum kidney cells.Pfiuegers Arch. 412:551–553
Yamaguchi, D.T., Green, J., Kleeman, C.R., Muallem, S. 1989. Characterization of volume-sensitive, calcium-permeating pathways in the osteosarcoma cell line UMR-106-01.J. Biol. Chem. 264:4383–4390
Yang, X. 1989. Characterization of Stretch-Activated Ion Channels inXenopus Oocytes. Ph.D. Thesis. University of Buffalo, Buffalo
Ypey, D.L., Ravesloot, J.H., Buisman, H.P., Nijweide, P.J. 1988. Voltage-activated ionic channels and conductances in embryonic chick osteoblast cultures.J. Membrane Biol. 101:141–150
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Davidson, R.M. Membrane stretch activates a high-conductance K+ channel in G292 osteoblastic-like cells. J. Membrain Biol. 131, 81–92 (1993). https://doi.org/10.1007/BF02258536
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DOI: https://doi.org/10.1007/BF02258536