45Ca2+ uptake in rat brain neurons: absence of sensitivity to the Ca2+ channel ligands nitrendipine and Bay K 8644.
K+-stimulated 45Ca2+ uptake into intact rat brain cells was biphasic, consisting of a fast first phase and a slow second phase; the latter was Na+ dependent. Cobalt and cadmium at 10(-4) and 10(-3) M produced 19-97% block of first phase 45Ca2+ uptake, but nitrendipine (to 10(-6) M) and Bay K 8644 (to 10(-6) M) were without effect on uptake and were similarly without effect in cells prepared in the presence of ATP, cAMP, Mg2+, and protease inhibitors. The second phase of K+-stimulated 45Ca2+ uptake was inhibited by 3,4-dichlorobenzamil (IC50, 29.6 microM). Depolarization-induced 45Ca2+ uptake into intact rat brain cells occurs by at least two different mechanisms. The first phase probably represents uptake through 1,4-dihydropyridine-insensitive Ca2+ channels, while the second phase is probably due to Na+-Ca2+ exchange.
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D002413:Cations, Divalent; D003035:Cobalt / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009568:Nitrendipine / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D051381:Rats
D002132:Calcium Radioisotopes; D002413:Cations, Divalent; D002104:Cadmium; D003035:Cobalt; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009568:Nitrendipine; D011188:Potassium; D002118:Calcium