Putative cardiotoxicity of the venoms of three mamba species.

The venoms of all mamba species are known to contain potent neurotoxins. Some authors suggest that cardiotoxins from mamba venom are responsible for heart failure in envenomated patients. This study was undertaken to come to a better understanding of the mechanisms and possible effects of mamba venom on the hearts of animals. The venoms of three mamba species namely Dendroaspis polylepis, Dendroaspis angusticeps, and Dendroaspis jamesoni were screened for cardiotoxicity by the cardiomyocyte viability test on cardiomyocytes isolated enzymatically from guinea pig ventricle muscle. This analysis was followed by an electrophysiological evaluation of the effects of venoms (from the Dendroaspis species) on cardiac ion channels by employing the whole-cell clamp procedure. In this study the cardiomyocyte viability test indicates differences among the venoms of the three mamba species. The venom of D. jamesoni seems to be the most potent followed by D. angusticeps and then D. polylepis. The whole-cell clamp results indicate that the venoms have no affinity for cardiac potassium channels but have an inhibitory influence on cardiac L-calcium channels. Although this study provides evidence that mamba venoms have a specific effect on isolated myocytes of guinea pig, it is doubtful that it will have a profound influence on a human heart in case of envenomation.