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.
Farrugia
G
G
Department of Physiology and Biophysics, Mayo Foundation, Rochester, Minnesota 55905.
Rae
J
J
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