Abstract
The volumes of acinar cells isolated from rat lacrimal gland were measured on computer by video-imaging. Cells were found to swell on exposure to hypotonic solutions; they subsequently exhibited a regulatory volume decrease (RVD). RVD was inhibited in the absence of extracellular Ca2+, and by the K+ channel blocker tetraethylammonium chloride (2 mm TEA+). The possible involvement of K+ channels in RVD was further investigated in cell-attached patches. Exposing the cells to a hypotonic solution activated channels with a conductance of 141±6 pS (n=11). These channels were partially blocked by 0.5 mm TEA+, and channel activation was not observed in the absence of extracellular Ca2+. Experiments in the inside-out patch configuration demonstrated that the channels activated by hypotonie stress were “maxi” Ca2+-activated K+ channels. It is concluded that the opening of these channels plays an important role in RVD, by facilitating K+ loss from the cell.
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We thank Dr. T. Kotera for helpful advice. We are also grateful to Dr. A. C. Elliott for his comments on the manuscript. K.-P.P. was a Visiting Academic Fellow supported by the University of Manchester, Faculty of Medicine Bequest Fund. J.S.B. was a Wellcome Research Fellow, and I.J.D. is an MRC Postgraduate Scholar. This work was supported by the Wellcome Trust (Grants: 037321/Z/92 and 035713/Z/92).
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Park, K.P., Beck, J.S., Douglas, I.J. et al. Ca2+-activated K+ channels are involved in regulatory volume decrease in acinar cells isolated from the rat lacrimal gland. J. Membarin Biol. 141, 193–201 (1994). https://doi.org/10.1007/BF00238253
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DOI: https://doi.org/10.1007/BF00238253