Pharmacological studies on the bungarotoxins: separation of the fractions and their neuromuscular activity

A commercial sample of Bungarus multicinctus venom was separated into its constituent fractions by column chromatography on CM-Sephadex C-50. The fractions were tested on the responses of the chick biventer cervicis preparation to nerve stimulation, and to added acetylcholine and carbachol. 13 fractions were obtained: 1 was inactive, 4 exhibited weak postjunctional neuromuscular blocking activity, 3 had potent postjunctional blocking activity, and the remaining 5 fractions exhibited predominately prejunctional blocking activity. Use of higher concentrations of the prejunctional toxins revelead that 2 of these fractions also possessed some postjunctional blocking activity. Because small differences in separation procedures may result in differences in the elution pattern of the venom, and because some fractions may possess nonspecific actions only obvious at high concentrations, it is suggested that, when using venom components as experimental tools, the separation method is detalied and the fractions thoroughly tested.