Lead Enters Bovine Adrenal Medullary Cells Through Calcium Channels |
| |
Authors: | T. J. B. Simons G. Pocock |
| |
Affiliation: | MRC Secretory Mechanisms Group, Department of Physiology, King's College, London;Department of Physiology, Royal Free Hospital School of Medicine, London, England |
| |
Abstract: | Agents that stimulate secretion also accelerate the rate of Pb uptake into adrenal medullary cells. For example, when cells are suspended in a medium containing 5 microM Pb2+, depolarization by 77 mM K increases the rate of Pb uptake from 12 +/- 1 to 47 +/- 5 mumol/(L cells X min). K-induced Pb uptake has an apparent Km for Pb2+ of 2.6 microM, and is antagonized by Ca2+ with a K0.5 of 1.4 mM. The Ca channel blocker D-600 inhibits Pb entry with a K0.5 of 0.4 microM. Pb uptake is also stimulated by the Ca channel agonist BAY K 8644. These observations suggest that Pb passes through Ca channels. The permeability of the channels to Pb appears to be at least 10 times the permeability to Ca. |
| |
Keywords: | Adrenal medulla Calcium channel Lead uptake |
|
|