THE ACTION OF THE TOXIN OF PRYMNESIUM PARVUM CARTER ON THE GUINEA‐PIG ILEUM

Abstract

The ichthyotoxin from Prymnesium parvum caused a slow contraction of the guinea‐pig isolated ileum preparation, followed by decreased sensitivity to acetylcholine and to 5‐hydroxytryptamine. These effects were reversed by washing. Administration of toxin was followed by insensitivity to further toxin. It was possible that a cholinergic transmitter participated in the contractions of the gut as this action was reduced both by atropine and by morphine. Illumination with visible light or warming a solution of toxin destroyed its antiacetylcholine activity before abolishing its stimulant action on gut. The crude extract of Prymnesium parvum may contain a mixture of active substances with different pharmacological actions. 1964 British Pharmacological Society