Differential coupling of voltage-gated Ca2+ channels to catecholamine secretion from separate PC12 cell batches

Amperometric recordings were employed to investigate the coupling of Ca2+ c hannels to catecholamine secretion in two batches of pheochromocytoma (PC12 ) cells. In 'new' (freshly obtained) cells (PC12n cells), secretion was dep endent on Ca2+ influx through L-type and N-type Ca2+ channels. By contrast, in 'aged' cells (maintained in liquid nitrogen for 6-8 years; PC12a cells) , secretion was mostly dependent on Ca2+ influx through N-type channels. Pa tch clamp recordings revealed that L-type channels accounted for only ca. 2 6% of total whole-cell current in PC12a cells (determined by blockade cause d by 2 muM nifedipine). In contrast, nifedipine suppressed currents by ca. 59% in PC12n cells. Thus important differences in fundamental physiological properties can be observed in PC12 cell batches even when obtained from th e same source and maintained under identical conditions. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.