Pb2+ activates potassium currents in bovine adrenal chromaffin cells.
Inorganic lead (Pb2+) is a potent environmental toxin which adversely affects several aspects of neuronal and secretory cell function. In this report, we provide evidence that at subnanomolar concentrations, Pb2+ activates the outward K+ currents in bovine adrenal chromaffin cells. Whole-cell patch clamp combined with intracellular perfusion was employed to monitor outward K+ currents in bovine chromaffin cells before and after intracellular application of EGTA-Pb buffers. Intracellular Pb2+ > or = 10(-10) M enhanced the K(+)-currents in a concentration dependent manner, with apparent K0.5 approximately equal to 5 x 10(-10) M. Extracellular application of 40 nM Charybdotoxin (ChTX) blocked the Pb(2+)-dependent component of outward currents, suggesting that Pb2+ activates the large conductance Ca(2+)-dependent K+ channels.
Sun
L R
LR
Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, OH 45267-0576.
Suszkiw
J B
JB
D000311:Adrenal Glands / Q000166:cytology / Q000502:physiology*; D000818:Animals; D002021:Buffers; D002417:Cattle; D002478:Cells, Cultured; D018999:Charybdotoxin; D002838:Chromaffin System / Q000166:cytology / Q000502:physiology*; D004533:Egtazic Acid / Q000494:pharmacology; D004553:Electric Conductivity; D007854:Lead / Q000494:pharmacology*; D011188:Potassium / Q000502:physiology*; D012604:Scorpion Venoms / Q000494:pharmacology
D002021:Buffers; D012604:Scorpion Venoms; D018999:Charybdotoxin; D007854:Lead; D004533:Egtazic Acid; D011188:Potassium