A large conductance K(+)-selective channel of guinea pig villus enterocytes is Ca2+ independent.
The presence of K(+)-selective channels has been probed in enterocytes isolated from guinea pig small intestinal villi by the patch-clamp technique. A channel with a single-channel conductance of approximately 130 pS was observed in excised inside-out patches bathed in symmetrical K+. A change in the K+ concentration in the intracellular aspect of the membrane altered the current-voltage relationship as expected from the constant-field equation when it is assumed that K+ is the only permeant ion. A change in Cl- concentration was without effect. Neither the activity of the channel nor its conductance was altered by addition of ATP or Ba2+ to the intracellular side of the patches. Changes in the free Ca2+ concentration were also without effect. The channel's open probability showed no voltage dependence and appeared only occasionally active in cell-attached patches where it had a linear current-voltage relation. The K+ channel described, which cannot be readily classified in any of the known classes of K+ channels, might provide an exit pathway for K+ recycling in guinea pig villus enterocytes.
Mintenig
G M
GM
Agricultural and Food Research Council Institute of Animal Physiology and Genetics Research, Cambridge, United Kingdom.
Monaghan
A S
AS
Sepúlveda
F V
FV
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000502:physiology*; D004594:Electrophysiology; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000166:cytology; D008871:Microvilli / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism* / Q000502:physiology
D015221:Potassium Channels; D011188:Potassium; D002118:Calcium