[Phalloidin antagonists 4th communication: Thioctic acid, SH-compounds, rifampicin, choleretics, dexamethasone, estradiol, unspecific inhibitors, and ineffective compounds (author's transl)].

1. Thioctic acid used clinically in poisoning by A. phalloides, protected perfused livers and also isolated hepatocytes against phalloidin, when given in high concentrations. 2. Some SH-compounds like coenzyme A, dimercaprol, cysteine and cysteamine were found to be protective in different concentrations. 3. Rifampicin protects mice against lethal doses of phalloidin, and inhibits poisoning of isolated hepatocytes at low concentrations. 4. Some choleretic drugs like dehydrocholate, temoebilin (extr. cucumae xanth.), ethacrynic acid influenced phalloidin poisoning by inhibition of binding. 5. Doses of 0.2 to 4.0 mg dexamethasone added to 100 ml of perfusion medium did not protect perfused rat livers against 0.5 mg phalloidin. 6. Pretreatment of female rats with estrogens effected protection against phalloidin in vivo. The same procedure resulted in moderate decrease of phalloidin effects when the livers of pretreated animals were poisoned in vitro. In male rats estrogen pretreatment was less effective. Castration did not augment the protective effect. 7. Secophalloidin, a biologically inactive derivative, did not influence phalloidin poisoning in perfused livers, even when applied in excessive concentrations. 8. Concanavalin A, probably bound in the neighborhood of binding sites for phalloidin, did not protect perfused livers against phalloidin. 9 Diethyldithiocarbamate, a compound protecting livers against carbon tetrachloride and halothane, was ineffective in phalloidin poisoning. 10. Further protective actions of Evans blue, of some phenanthrolines and of EDTA are discussed. 11. Pretreatment of animals with hepatotoxic compounds (CCl4, CHCl3, cinchophen) decreased the toxicity of phalloidin in vivo. Possible mechanisms are discussed.