Anthopleurin-C (APE2-1). A Potent Activator of Nav Channels. A potent cardiotoxin, which evokes a positive inotropic and chronotropic effect on mammalian heart muscle. Recently it was found that this toxin modifies the current passing through the fast Na+ channel in neuroblastoma cells, leading to delay and incomplete inactivation. Effective at concentrations of 1-5nM in isolated guinea-pig atria. Ion Channel Modulators; Voltage - Gated Na+ Channel Activators.