Effect of volume changes on a potassium current in rabbit corneal epithelial cells.
Patch-clamp recordings from rabbit corneal epithelial cells have identified a large-conductance (167 pS in symmetrical 150 mM KCl) K channel that is the major contributor to the whole cell current (J. L. Rae and G. Farrugia. J. Membr. Biol. 129: 81-87, 1992). We report here on the regulation of this channel by changes in cellular osmolality and/or volume. Exchanging the bath solution with a hyposmotic (225 or 150 mosM) solution resulted in cellular swelling and selective activation of the K current (126 +/- 86 and 273 +/- 184% increase, respectively). Hyperosmotic solution changes (380 mosM) resulted in cell shrinkage and deactivation of the K current (44.2 +/- 21% decrease). Similar increases in the cell volume and whole cell current were observed on increasing (in perforated patch experiments) the chloride ion concentration (50 mM) in the pipette intracellular solution (127 +/- 63% increase). These changes were accompanied by marked shifts in the resting membrane voltage. We conclude that the K channels in these cells can respond to alteration in cellular osmolality or volume, resulting in changes in the whole cell current and resting voltage.
Department of Physiology and Biophysics, Mayo Foundation, Rochester, Minnesota 55905.
G
G
Farrugia
J
J
Rae
D000818:Animals; D003315:Cornea / Q000502:physiology*; D004110:Diltiazem / Q000494:pharmacology; D004848:Epithelium / Q000502:physiology; D006982:Hypertonic Solutions; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009994:Osmolar Concentration; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011817:Rabbits
D006982:Hypertonic Solutions; D015221:Potassium Channels; D004110:Diltiazem