ω-conotoxin SO-3

ω-conotoxin SO-3 is a selective blocker of N-type voltage-sensitive calcium channels. EC50 for ω-conotoxin SO-3 is 0.16 µM (similar to ω-conotoxin MVIIA) on HVA calcium currents. ω-conotoxin SO-3 did not show any inhibiting effects on L-type, P/Q-type and R-type currents at 3 µM concentration. ω-conotoxin SO-3 has no effect on voltage-sensitive sodium currents, delayed rectifier potassium currents and transient outward potassium currents. At 3 µM, the inhibition amounts of HVA ICa was very similar between ω-conotoxin SO-3 and ω-conotoxin MVIIA (~ 32%). Their inhibitory effects are almost fully reversible but their half-time for recovery are different (~ 7.5 min for ω-conotoxin SO-3 and ~ 4.14 min for ω-conotoxin MVIIA). ω-conotoxin SO-3 displays an analgesic potency similar to ω-conotoxin MVIIA in a range of acute and chronic pain models in rodents, but has less adverse effects compared with identical dosages of ω-conotoxin MVIIAinjected intrathecally.