Modulation of Ca2+- and voltage-activated K+ channels by internal Mg2+ in salivary acinar cells.
High-conductance K+ channels are known to be activated by internal Ca2+ and membrane depolarization. The effects of changes in internal Mg2+ concentration have now been investigated in patch-clamp single-channel current experiments on excised membrane fragments from mouse acinar cells. It is shown that Mg2+ in the concentration range 10(-6)-10(-3) M evokes a dose-dependent K+ channel activation at a constant Ca2+ concentration of 10(-8) M. The demonstration that changes in [Mg2+]i between 2.5 X 10(-4) and 1.13 X 10(-3) M has effects on the channel open-state probability indicates that fluctuations in [Mg2+]i in intact cells may influence the control of channel opening.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D051379:Mice; D010306:Parotid Gland / Q000166:cytology / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*
D007473:Ion Channels; D004533:Egtazic Acid; D008274:Magnesium; D011188:Potassium; D002118:Calcium