Objective To isolate and charaterize the
neurotoxic fractions from Ophiophagus hannah venom. Methods CM-Sephadex C-50 column
was used to isolate the venom with step-wise elution. The
fractions were purified by Sephadex G-50. Neurotoxicity was determined on isolated rat phrenic nerve-diaphragm preparations. Effects of
Neurotoxic fractions on acetylcholine-induced contractile response of the isolated frog rectus abdominis were observed. The LD-{50} of neurotoxic fractions was determined by Meier and Theakston method. Results Forteen fractions(A~N) were isolated from Ophiophagus hannah venom, six fractions(E, F, G, H, I and K) of which are neurotoxic and occupied the content of 48 3%. Fraction E, G and K produced a concentration-dependent parallel shift to the right of dose-response curve of acetylcholine applied exogenously with no change in the maximal asymptotic response. The dissolation constant K-D of N-2-AchR in fraction E, G and K were 145 87, 73 53 and 20 04 ng/mL, respectively. The LD-{50} of fraction E, G and K in mice(iv) were 0 884, 0 749 and 1 58 mg/kg respectively. Conclusion Six neurotoxic fractions were isolated from Ophiophagus hannah venom(from Fujian). Three fractions(E, G and K) were determined as the competitive antagonists of N-2-AchR.;