Cardiotoxic Effects of Lachesis acrochorda Snake Venom in Anesthetized Wistar Rats

Abstract

Ophidism is a public health problem in tropical countries, occurring predominantly in rural areas. In Colombia, among the species responsible for snakebite envenomation, inflicting high mortality, is the Chocoan bushmaster, Lachesis acrochorda, better known locally by the names "verrugosa (warty)" and "pudridora (rot-causing)". In this research, the cardiotoxic effect of the venom of L. acrochorda in male Wistar rats weighing 230 ± 20 g was evaluated. A statistical design of randomized blocks was implemented with three treated groups, injected with lyophilized venom (doses of 3.22 μg/g, 6.43 μg/g, 12.86 μg/g), and a control group injected with 0.9% saline solution. Electrocardiographic (ECG) recordings were taken from the anesthetized animals, revealing an increase in the amplitude of the P and T waves and an increase in the duration of the QT intervals in the electrocardiographic recordings. These increases were not observed in the control biomodels. In the analysis of the CK and CK-MB enzyme levels, increases were also observed in the levels of cardiac isoenzymes in the injected animals, but none in the control animals. The histopathological analyses carried out reveal that the injected animals showed effects such as interfibrillar and perivascular edema, cellular shortening of the cardiomyocytes, foci with tissue destructuring, and necrosis with contraction bands. In conclusion, the venom of the Lachesis acrochorda snake increases the P and T waves and the QT interval and increases the CK and CK-MB enzymes in the blood. Additionally, it causes interfibrillar and perivascular edema in the cardiac tissue, cardiocytolysis, and contraction bands.

Keywords: Lachesis acrochorda; Rattus norvegicus; cardiotoxic; snake venom.

Figure 1

Alterations in the P wave. (A) Normal ECG recording in a control rat; (B) ECG recording in rats injected with L. acrochorda venom (SVLa), indicating the abnormal elevation of the P wave; (C) two-way ANOVA statistical analysis, comparing the values of the P wave amplitude across the time blocks (hours) and doses of SVLa with those of the control group. ** Highly significant difference, *** Extremely significant difference.

Figure 2

Alterations in the T wave. (A) Normal ECG recording in a control rat; (B) ECG recording in rats injected with SVLa, indicating increased T wave; (C) two-way ANOVA statistical analysis. *** Extremely significant difference.

Figure 3

Alterations in the duration of the QT interval. (A) Normal ECG recording in a control rat; (B) ECG recording in rats injected with SVLa, indicating increased QT interval; (C) two-way ANOVA statistical analysis, contrasting the values of the T wave amplitude in each of the time blocks (hours) and groups (control and SVLa doses of 3.22 μg/g, 6.43 μg/g, 12.86 μg/g), showing a highly significant difference (p < 0.005) between the T wave amplitude of the controls and that of the dosed ones, with the greatest elevation occurring at 2 and 3 h. ** Highly significant difference, *** Extremely significant difference.

Figure 4

Alterations in heart rate. A one-way ANOVA analysis was conducted for the heart rate shown by the rats in the control group and those receiving doses of SVLa (3.22 μg/g, 6.43 μg/g, 12.86 μg/g), after performing Dunnett’s test. * Significant difference, *** Extremely significant difference. Contrl group purple bar, dose of 0.22 μg/g green bar, dose of 6.43 μg/g blue bar, dose of 12.86 μg/g red bar.

Figure 5

Striated muscle (CK) and myocardial fraction (CK-MB) enzymes. (A) CK and CK-MB values for each of the doses used; (B) two-way ANOVA contrast of the blood concentration values of the CK-MB isoenzyme at the first and fourth hours after inoculation with SVLa. *** Extremely significant difference.

Figure 6

Interfibrillar edema. (A) Normal tissue from control rats; (B) tissue with the presence of mild interfibrillar edema (rats injected with a dose of SVLa at 3.22 μg/g); (C) tissue with the presence of moderate interfibrillar edema (rats injected with a dose of SVLa at 6.43 μg/g); (D) tissue with severe interfibrillar edema (rats injected with a dose of SVLa at 12.86 μg/g), H-E 40X; (E) statistical analysis of edema by the Chi-squared test. *** Extremely significant difference.

Figure 7

Cardiocytolysis. (A) Normal tissue from control rats; (B) tissue with destructuring, necrosis with contraction bands, H-E 40X; (C) statistical analysis of the presence of cardiocytolysis by the Chi-squared test. ** Highly significant difference.

Figure 8

Contraction bands. (A) normal tissue from control rats; (B) tissue with disorganization of its cytoarchitecture, shortened cardiomyocytes, and contraction bands, H-E 40X; (C) statistical analysis of the presence of contraction bands by the Chi-squared test, indicating that the level of alteration depends on the dose applied. ** Highly significant difference.