INVOLVEMENT OF DIHYDROPYRIDINE-SENSITIVE CALCIUM CHANNELS IN NERVE GROWTH FACTOR-DEPENDENT NEURITE OUTGROWTH BY SYMPATHETIC NEURONS

We have used a number of pharmacological manipulations of calcium influx to alteeer the nerve growth factor (NGF)‐elicited neurite outgrowth response of SCG neurons. Our results indecate that influx of extracellular calcium is critical to sympathetic SCG neurite outgrowth. Effective blockade of this process was produced by the inorganic calcium channel blockers Cd2+ (with an IC50 of 48μM), Co2+ (129μM), and Ni2+ (180 μM). More specifically, there is a significant contribution from dihydropyridine‐sensitive L‐type calcium channels to NGF‐activated neurite outgrowth, as evidenced by the significant inhibition of neurite outgrowth by diltiazem (IC50 of 17μM) and nifedipine (3μM). Further, increases in calcium influx can elicit an enhanced neurite outgrowth response, as shown by the calcium channel agonist Bay K 8644 wich potentiated neurite outgrowth by up to 40%. Copyright © 1990 Wiley‐Liss, Inc.