Rectification of acetylcholine-elicited currents in PC12 pheochromocytoma cells.
The current-voltage (I-V) relationship for acetylcholine-elicited currents in the rat pheochromocytoma cell line PC12 is nonlinear. Two voltage-dependent processes that could account for the whole-cell current rectification were examined, receptor channel gating and single receptor channel permeation. We found that both factors are involved in the rectification of the whole-cell currents. The voltage dependence of channel gating determines the shape of the I-V curve at negative potentials. The single-channel I-V relationship is inwardly rectifying and largely responsible for the characteristic shape of the whole-cell I-V curve at positive potentials. The rectification of the single-channel currents is produced by the voltage-dependent block of outward currents by intracellular Mg2+ ions.
Division of Biomedical Sciences, Washington University School of Medicine, Saint Louis, MO 63110.
C K
CK
Ifune
J H
JH
Steinbach
D000109:Acetylcholine / Q000494:pharmacology*; D000310:Adrenal Gland Neoplasms; D000818:Animals; D002460:Cell Line; D004553:Electric Conductivity; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D010673:Pheochromocytoma; D051381:Rats; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000502:physiology*
D007473:Ion Channels; D000109:Acetylcholine