Characteristics of the action of Crotalus horridus horridus (timber rattlesnake) venom on the isolated, perfused rat heart.
The isolated Langendorff-perfused heart was used to examine the effects of a 4 min infusion of Crotalus horridus horridus venom (3.3-33 micrograms/ml) on various physiological, biochemical and morphological parameters. Venom infusion reduced ventricular contractility in a dose-dependent manner that was not reversible; this response was markedly attenuated by either lowering the temperature from 37 degrees C to 32 degrees C or the perfusate potassium ion concentration from 5.9 to 2.5 mM. The negative inotropic response was not associated with any change in heart rate or coronary flow. Envenomation induced a progressive fall in ECG amplitude without effect on P and Q waves and a variable delayed incidence of premature ventricular complexes. Light microscopy showed localized, patchy areas of degenerating fibres within the ventricular mass by 5 min. Ventricular tissue ATP, ADP and lactate content were not significantly changed at this time. Crotamine was without effect on the heart. Another venom component apparently has a direct effect on the heart to disrupt the integrity of ventricular fibres.
Department of Physiology, King's College London, U.K.
R
R
Kempsford
B J
BJ
Hawgood
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects; D003435:Crotalid Venoms / Q000494:pharmacology / Q000633:toxicity*; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000033:anatomy & histology / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D007773:Lactates / Q000378:metabolism; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism; D010477:Perfusion; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D003435:Crotalid Venoms; D007773:Lactates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; C010563:crotamine; D011188:Potassium