ABSTRACT
Three fractions were isolated from the venom of Dendroaspis angusticeps by column chromatography on CM-Sephadex C-25. All the three fractions were shown to possess acetylcholinesterase inhibiting activity. The toxicity of the fractions as tested on mice were variable. Although the toxic signs were identical, fraction DaVI was highly lethal (LD50 1.9 microgram/g) whereas fractions DaIV and T39 were less lethal, the LD50 being 3.6 micrograms/g and 4.1 micrograms/g respectively. The three fractions significantly inhibited true acetylcholinesterase to the extent of 91-95%.
Subject(s)
Cholinesterase Inhibitors/isolation & purification , Elapid Venoms/isolation & purification , Acetylcholinesterase , Animals , Cholinesterase Inhibitors/metabolism , Chromatography , Mice , RatsABSTRACT
Dendroaspis angusticeps venom (75 micrograms/ml) caused an irreversible blockade of the directly as well as directly evoked contractions of the rat hemidiaphragm and indirectly evoked contractions of the chick biventer cervicis muscle. The venom itself also produced a contraction of the frog rectus abdominis muscle, rat fundal strip, rat uterus and nictitating membrane of the cat; however, it did alter responses of nictitating membrane to preganglionic electrical stimulation and to ganglion stimulant drugs. The effect was attributed to the presence of acetylcholine-like substance in the venom.
Subject(s)
Elapid Venoms/pharmacology , Muscle Contraction/drug effects , Animals , Cats , Chickens , Electric Stimulation , Female , In Vitro Techniques , Jejunum/physiology , Rabbits , Ranidae , Rats , Rats, Inbred Strains , Uterine Contraction/drug effectsABSTRACT
Whole venom Dendroaspis angusticeps produced a negative chronotropic and ionotropic effect on the heart. Isolation of the fraction (T39) produced the same effect. Negative inotropic effect was blocked by atropine. The bradycardia may be due to a cholinergic effect and the negative ionotropic to a direct depressant effect on the myocardium.
Subject(s)
Elapid Venoms/pharmacology , Heart Rate/drug effects , Myocardial Contraction/drug effects , Animals , Atropine/pharmacology , Depression, Chemical , In Vitro Techniques , Rabbits , Time FactorsABSTRACT
Lateral ventricular administration of 100 microgram of Dendroaspis polylepis venom is cats consistently produced a marked rise in arterial blood pressure, heart rate dilatation of pupils and piloerection. This intense central sympathetic discharge occurred after a latent period of 11.7 +/- 0.72 min. Bilateral adrenelectomy abolished the sympathetic discharge showing that central release of catecholamines from the adrenal medulla may play an important role in elicting the cardiovascular response.
