Studies on Cardiotoxin and Vasoactive-Substance-Releasing
Abstract
Lyophilized venom of Naja naja atra was fractionated on column of CM- Sephadex (G-50) into 13 fractions by gradient elution with ammonium acetate buffer at pH 5-7. Among them five fractions (V-IX) were found to be neurotoxic and three (X, XII, XIII) were cardiotoxic. Intraperitoneal LD50 in mice was 0. 074 micrograms g/g for FR. VIII-the major neurotoxic component (NT) and 1.48 micrograms g/g for Fr. XIII-the major cardiotoxic one (CT). CT caused contracture, as well as reduction of resting membrane potentials, of the frog's sartorius, chick's biventer cervicis, and rat's diaphragm. In the absence of calcium, the contracture was markedly reduced, although the depolarizing effect remained unchanged. Neither contracture nor depolarization was caused by NT. The terminal nerve spikes of the frog sartorius were abolished by CT but unaffected by NT. CT caused systolic arrest of isolated frog hearts and rat's atria by reducing the membrane potentials, whereas NT was almost without effect up to . 0001 g/ml. CT caused a slow contraction of the guinea pig ileum, which was partially antagonized by either atropine or procaine but not by hexamethonium or antihistaminics. The vessels of the rabbit ear were constricted by CT. In cats, CT caused a fall in systolic pressure more than diastolic pressure, accompanied by various ECG changes. Cardiotoxin isolated from cobra venom acts on various excitable cells, predominantly, of not entirely, by reducing the membrane potentials.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 15, 1966
- Accession Number
- ADA955164
Entities
People
- Chen-yuan Lee
Organizations
- National Taiwan University