Inactivation of 45Ca2+ uptake by prior depolarization of PC12 cells.
45Ca2+ uptake evoked by depolarization of PC12 pheochromocytoma cells with K+ was reduced approximately 90% by prior depolarization in Ca2+-containing medium. Prior depolarization without added Ca2+ reduced 45Ca2+ uptake by only about 20%. The Ca2+ channel agonists, BAY K 8644 and CGP 28392, had no effect on inactivation of 45Ca2+ uptake. These findings suggest that (1) voltage-gated Ca2+ channels of PC12 cells undergo inactivation, (2) inactivation is Ca2+-dependent rather than voltage-dependent, and (3) Ca2+ channel agonists do do not promote Ca2+ flux by inhibiting Ca2+ channel inactivation.
D A
DA
Greenberg
C L
CL
Carpenter
R O
RO
Messing
D000818:Animals; D001693:Biological Transport, Active; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002132:Calcium Radioisotopes / Q000378:metabolism*; D002460:Cell Line; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D008564:Membrane Potentials; D009447:Neuroblastoma / Q000378:metabolism; D010673:Pheochromocytoma / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D013997:Time Factors
D002121:Calcium Channel Blockers; D002132:Calcium Radioisotopes; D007473:Ion Channels; D011188:Potassium