Involvement of the Ca2+-dependent K+ channel activity in the hyperpolarizing response induced by epidermal growth factor in mammary epithelial cells.
Epidermal growth factor (EGF) induces a hyperpolarizing response of 5-20 mV amplitude in mouse mammary epithelial cells in culture. The amplitude of the hyperpolarizing response was reduced by more than 60% within several minutes after addition of blockers of voltage and/or Ca2+-dependent K+ channels such as tetraethylammonium (7 mM) or quinine (0.29 mM). Both nifedipine (0.15 mM), a blocker of the Ca2+ channel, and ruthenium red (2 mM), an inhibitor of the Ca2+-binding site, also reduced the amplitude of the hyperpolarizing response by more than 60%. The Ca2+ ionophore, A23187 (3.8 microM), induced a large hyperpolarization, which was 25-40 mV and lasted about 3 min. These data suggest that activity of the Ca2+-dependent K+ channel was involved in the EGF-induced hyperpolarizing response of the mammary epithelial cells.
D000818:Animals; D002118:Calcium / Q000502:physiology*; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D004848:Epithelium / Q000502:physiology; D005260:Female; D007473:Ion Channels / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009543:Nifedipine / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D011803:Quinine / Q000494:pharmacology; D012430:Ruthenium Red / Q000494:pharmacology; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D012430:Ruthenium Red; D004815:Epidermal Growth Factor; D011803:Quinine; D009543:Nifedipine; D011188:Potassium; D002118:Calcium