Cevadine, veratridine, and related lipophilic ceveratrum alkaloids cause activation of the voltage-sensitive Na+ channels of nerve, heart, and skeletal muscle cell membranes similar to pyrethrins. Both veratridine and cevadine alter the ion selectivity of Na+ channels and cause persistent activation. The receptor for these alkaloids has not been isolated, but experiments indicate it is distinct from that of pyrethrin. Structurally, veratridine and cevadine differ only in their acyl group. Cevadine has been used as an insecticide, acting as a paralytic agent with higher toxicity to insects than to mammals. It has been used to study Na+ channel blockers such as vincamine and vincanol by inducing Na+ channels in the presence and absence of the drugs being tested.