THE ACTION OF WATER MOCCASIN VENOM ON THE ISOLATED FROG HEART

Abstract

Venom of the water moccasin, Agkistrodon piscivorus, was collected by milking, dried, ground, and the various batches mixed. Venom solns. were all made in Ringer soln. Hearts of spring and summer frogs were treated by a modified Straub technique. With 1:1000 venom soln., rate and amplitude decreased to zero in 18 min. With 1:10,000 solns., preliminary slowing (abolished by atropine) occurred; amplitude was increased; rate recovered, then progressively decreased; amplitude fell to zero. Failure occurred in 24 min. With 1:100,000 solns., some hearts showed prelim. stim., others showed initial slowing; failure occurred in 120 min. 1:1,000,000 solns. in several expts. showed slight initial slowing; this was absent in others; efficiency exceeded that of controls throughout exptl. period (180 min.). The ventricle failed first, the atria next, last the sinus venosus. The ventricles stopped in contraction (except a few in 10-6 solns.) and were opaque. Atria stopped in extreme dilatation in all expts; they were opaque. The sinus venosus remained clear. Contractures and muscular irregularities occurred in all but 10-6 solns. Dissociation rarely occurred. Venom solns. rendered all atria extremely permeable (shown by fluid loss through walls). The venom is toxic to endocardium, myocardium and probably the intrinsic ganglia. The author thinks venom acts directly on the above tissues.