Sarafotoxin 6C (S6C) is an isoform of a toxin found in the venom of Atractaspis engaddensis snakes. S6C acts as a peptide agonist at endothelin B (ET-B) receptors and exhibits anti-arrhythmic and cardiomodulatory activities. S6C can be vasodilatory, vasoconstrictive, cardiotoxic, or cardioprotective depending on the model being studied. When administered as a pretreatment prior to cerebral occlusion in animal models of cardiac ischemia/reperfusion, S6C induces NO release and activates mitoK(ATP) K+ channels, decreasing infarct size and arrhythmia occurrence and increasing overall survival rates. S6C also increases levels of superoxide anions in sympathetic ganglia and induces hypertension in some animal models. In vitro, S6C delays suicidal erythrocyte death, and in contracted aortic and vena cava rings, it induces relaxation.