Interaction of Ca-Channel Blockers and High Pressure at the CrustaceanNeuromuscular Junction. (Reannouncement with New Availability Information)

摘要

Exposure to high pressure causes a significant depression of synaptictransmission. We examined the effects of various Ca-channel blockers and their interaction with high pressure on excitatory neuromuscular junction currents (EJCs) of lobster abdominal muscles. Reduced Ca2+ to half of normal concentration or exposure to 40-60 uM CdCl2 10-20,uM NiCl2 and 1 uM w-conotoxin decreased EJCs by 50%. Nifedipine, Nitrendipine and Bay K-8644 were ineffective. Either Ca-blockers or reduced Ca2+, enhanced EJC suppression exerted by high pressure. The data suggest that high pressure primarily affects Ca2+ inflow at the presynaptic terminals through N-type voltage-gated Ca-channel.