Vasoconstrictor activity. These toxins cause cardiac arrest probably as a result of coronary vasospasm. The major effects of sarafotoxin-m are a progressive decrease in heart rate (bradycardia) that turns into an arrhythmic phase that is followed by an A-V block. Vasoconstrictor activity. Causes cardiac arrest probably as a result of coronary vasospasm (By similarity). Displays low agonistic activities towards endothelin-2 receptor (EDNRB) (displays affinity in the micromolar range) (PubMed:21889567). Expressed by the venom gland. LD(50) is 27-37 ug/kg by intravenous injection into mice. Belongs to the endothelin/sarafotoxin family.