Calcium permeability of nicotinic acetylcholine receptor channels in bovine adrenal chromaffin cells.
The fractional contribution of Ca to current flow through neuronal-type nicotinic acetylcholine receptor channels was determined by quantitative fluorescence microfluorimetry using fura-2. The method, which has been applied already to several types of cells and channels is described in detail here. At -70 mV and 2 mM external Ca concentration it was found that Ca contributes 2.5% to the net current. The fractional contribution was found to be voltage dependent, increasing at negative potentials e-fold for a 110 mV potential difference. Total non-specific cation current was found to have a bell-shaped dependence on external Ca concentration peaking at 2 mM.
Zhou
Z
Z
Department of Medicine, Jewish Hospital of St. Louis, MO 63110.
Neher
E
E
D000311:Adrenal Glands / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology; D015220:Calcium Channels / Q000502:physiology; D002417:Cattle; D002838:Chromaffin System / Q000166:cytology / Q000378:metabolism*; D004594:Electrophysiology; D016257:Fura-2; D015640:Ion Channel Gating; D007473:Ion Channels / Q000378:metabolism*; D010539:Permeability; D011978:Receptors, Nicotinic / Q000378:metabolism*
D015220:Calcium Channels; D007473:Ion Channels; D011978:Receptors, Nicotinic; D002118:Calcium; D016257:Fura-2