Modification of K channel inactivation by papain and N-bromoacetamide.
The whole-cell variation of the patch clamp technique was used to study macroscopic K current in voltage clamped GH3 cells. An inactivating, voltage-dependent K current was studied in isolation by inhibiting Ca-activated K currents with internal Ca chelators and external tetraethylammonium ions. Under control conditions, the K current inactivated in two phases with time constants of 25 and 79 ms. After treatment with either a proteolytic enzyme such as papain or the amino acid reagent N-bromoacetamide, the K current no longer inactivated rapidly, but decayed very slowly with a time constant of 500 to 750 ms. The action of papain or N-bromoacetamide on K channels is comparable to their action on Na channels, suggesting that inactivation in Na and K channels occurs by a similar mechanism.
Matteson
D R
DR
University of Maryland School of Medicine, Department of Biophysics, Baltimore 21201.
Carmeliet
P
P
D000081:Acetamides / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D004553:Electric Conductivity; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D010206:Papain / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism*
D000081:Acetamides; D007473:Ion Channels; C016272:N-bromoacetamide; D010206:Papain; D011188:Potassium