POISONINGS FROM FLESH OF THE GREENLAND SHARK SOMNIOSUS-MICROCEPHALUS MAY BE DUE TO TRIMETHYLAMINE

The flesh of the Greenland shark, Somniosus microcephalus, especially in fresh condition, is toxic to both dog and man. Analysis of the toxic fractions indicates the presence of large amounts of trimethylamine oxide (TMAO) but no other substances that could be directly responsible for the poisoning. The symptoms appear to be due to an acute trimethylamine (TMA) poisoning arising from intestinal reduction of TMAO to TMA. TMA stimulates contraction of the guinea-pig ileum (antagonized by atropine but not hexamethonium). Low concentrations of TMA increase contraction of the rat phrenic nerve-diaphragm preparation, whereas higher concentrations cause blockade.