Pharmacology of scorpion (Lychas laevifrons Pock) venom with special reference to its neuromuscular activity

L. laevifrons venom caused irreversible blockade of electrically induced twitch responses on phrenic nerve diaphragm and chick biventer cervicis preparation. The venom lowered cat blood pressure, caused a brief cardiac arrest and increased cutaneous capillary permeability. It contracted several smooth muscle preparations. The quick contraction produced on guinea pig ileum was partly antagonized by mepyramine and completely by methysergide. The residual slow contraction was antagonized by SC 19220, a prostaglandin blocker. Haemolysis was not produced by the venom on human RBC. LD50 of crude venom in mice was 13.8 mg/kg (iv).