title: Ca(2+)-activated K+ channels are involved in regulatory volume decrease in acinar cells isolated from the rat lacrimal gland.
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 hypotonic stress were "maxi" Ca(2+)-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.
authors: Cell Physiology and Renal Research Groups, School of Biological Sciences, University of Manchester, United Kingdom.
authors: K P
authors: KP
authors: Park
authors: J S
authors: JS
authors: Beck
authors: I J
authors: IJ
authors: Douglas
authors: P D
authors: PD
authors: Brown
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology* / Q000502:physiology; D006706:Homeostasis; D007038:Hypotonic Solutions; D066298:In Vitro Techniques; D007700:Kinetics; D007765:Lacrimal Apparatus / Q000166:cytology* / Q000502:physiology*; D008838:Microcomputers; D018715:Microscopy, Video; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D013997:Time Factors
chemical_list: D007038:Hypotonic Solutions; D015221:Potassium Channels; D002118:Calcium