Sodium and calcium fluxes in a clonal nerve cell line.

摘要: 1. 22Na+ and 45Ca2+ fluxes were studied in the clonal nerve cell line PC12. Three distinct types of ion channels found: (a) voltage-dependent Na+ channels, (b) Ca2+ (c) acetylcholine-activated permeable to both ions. 2. uptake through is induced by veratridine scorpion venom, inhibited 50% 5 X 10(-7) M-tetrodotoxin greater than 98% 10(-6) M-tetrodotoxin. 3. depolarizing cells 50 mM-KCl. This flux not dependent on presence medium insensitive However, 1 mM-Mn2+ causes a 95% inhibition K+-induced uptake. 4. Veratridine venom also induce which can be blocked 1mM-Mn2+. In contrast KCl-induced uptake, this completely abolished removal from medium. Thus stimulus for case influx channels. 5. Carbamylcholine induces are nicotinic cholinergic antagonists with exception alpha-bungarotoxin. The occurs exclusively via acetylcholine receptor as evidenced lack effect Na+, almost all thus activated influx. 6--8% total flux, however, mM-Mn2+, suggesting that portion Na+-free medium, Mn2+-resistant component increases 40% apparently due competition receptor-linked still sufficient depolarization additional 60% voltage-dependent, Mn2+ sensitive 6. inhibits competing entry these mM-KCl 54Mn2+ PC12 comparable magnitude fluxes. 7. normal saline efflux several times more rapid indicating Ca2+-Na+ exchange mechanism.