Quinine inhibits Ca2+-independent K+ channels whereas tetraethylammonium inhibits Ca2+-activated K+ channels in insulin-secreting cells.
The effects of quinine and tetraethylammonium (TEA) on single-channel K+ currents recorded from excised membrane patches of the insulin-secreting cell line RINm5F were investigated. When 100 microM quinine was applied to the external membrane surface K+ current flow through inward rectifier channels was abolished, while a separate voltage-activated high-conductance K+ channel was not significantly affected. On the other hand, 2 mM TEA abolished current flow through voltage-activated high-conductance K+ channels without influencing the inward rectifier K+ channel. Quinine is therefore not a specific inhibitor of Ca2+-activated K+ channels, but instead a good blocker of the Ca2+-independent K+ inward rectifier channel whereas TEA specifically inhibits the high-conductance voltage-activated K+ channel which is also Ca2+-activated.
Findlay
I
I
Dunne
M J
MJ
Ullrich
S
S
Wollheim
C B
CB
Petersen
O H
OH
D007516:Adenoma, Islet Cell / Q000503:physiopathology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D004553:Electric Conductivity; D007340:Insulinoma / Q000503:physiopathology*; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D010190:Pancreatic Neoplasms / Q000503:physiopathology*; D011188:Potassium / Q000378:metabolism*; D011803:Quinine / Q000494:pharmacology*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology*
D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium; D011803:Quinine; D011188:Potassium; D002118:Calcium