Omega-Grammotoxin SIA (Grammostola spatulata. A novel blocker to Cav2.1 (P-type) and Cav2.2 (N-type) voltage-gated Ca2+ Channels.
omega-Grammotoxin SIA is a native toxin isolated from venom of the South American Tarantula spider Grammostola spatulata. Omega-Grammotoxin SIA potently inhibits both Cav2.1 (P-type) and Cav2.2 (N-type) Ca2+ channels by altering the voltage-dependence of channel gating. Omega-Grammotoxin SIA caused a concentration-dependent and virtually complete inhibition of K+-evoked influx of Ca2+ into either rat or chick brain synaptosomes. Omega-Grammotoxin SIA at 1 μM, a maximally effective concentration, blocked 52% of IBa in cultured rat hippocampal neurons. A concentration of >50 nM toxin completely inhibited Ca2+�currents in Purkinje neurons (predominantly, P-type channels) and in sympathetic neurons (predominantly, N-type channels).
Ion Channel Modulators; Voltage - Gated Ca2+ Channel Blockers.