RESUMO
In the present study, we investigated the cardiotoxic potential of Micrurus frontalis venom. Twelve guinea pigs (Cavia porcellus) were distributed in two groups (n = 6), named control and envenomed. Control groups received 0.2 ml of PBS/BSA, while envenomed group received 0.2 ml of the same solution containing 450 µg/kg of M. frontalis venom. Both were intramuscular injections. Electrocardiography, echocardiogram, blood count, and serum biochemistry were performed before and 2 h after inoculation. Necropsy was performed, and histological and ultrastructural analysis of the heart were conducted. First clinical signs were presented as early as 18 min after venom inoculation. All poisoned animals presented flaccid paralysis of both hind and forelimbs, followed by fasciculations and respiratory arrythmia. However, the animals did not die in the first 2 h of poisoning. ECG of the poisoned animals revealed severe ventricular arrythmias, corroborated by reduction of both ejection and shortening fractions, increase in CK, CK-MB, troponin, cardiomyocyte degeneration, fragmentation and mitochondrial damage. M. frontalis venom causes severe heart damage, eliciting both morphological and arrhythmogenic effects after only 2 h of envenomation.