Pressor action of pyridine-2-aldoxime in malathion poisoning

1. Intravenous injections of pyridine-2-aldoxime (PAM) produced a marked, prolonged and dose-related rise in blood pressure in anaesthetized cats treated with malathion (MT) and without malathion (NMT). 2. The pressor effect of PAM was significantly reduced by phentolamine and phenoxygenzamine, but unaffected by hexamethonium. 3. Pretreatment with guanethidine and reserpine almost completely abolished the pressor response to PAM. 4. The results indicate that PAM has a potent sympathomimetic action which appears to be mediated through release of catecholamines from storage sites.