Adrenergic blocking agents and adrenal sympathetic discharge

Indolizidine and quinolizidine alkaloids

“…Pumiliotoxin B (72) ( = pumiliotoxin 323A) has been shown to induce epilepsy-like electric activity in guinea pig hippocampal slices by increasing the rate at which sodium ion channels open and close.56 Epileptogenic effects have been noted when skin extracts of the Australian frog Pseudophryne coriacea, a known source of pumiliotoxin B, were injected into areas of the rat brain, particularly the dorsal hippo~ampus.~' Extracts from the same source potentiated and prolonged bioelectric activity in the excitable tissue from mouse diaphragm, perhaps by mechanisms involving dual actions with both calcium and sodium ion channel^.^^ In the rabbit, a fleeting hypotensive effect after administration of Pseudophryne 'coriacea extracts was succeeded by an intense long-lasting rise in blood pressure and disturbances in cardiac rhythm. 59 The reversibility of the response suggests that pumiliotoxin B could be of pharmacological value in the study of antiarrhythmic drugs.…”