Vomiting, hypothermia, and respiratory paralysis due to tetrodotoxin (puffer fish poison) in the cat

Abstract

Crystalline tetrodotoxin (puffer fish poison) was administered to chronic cats by intravenous, intracerebroventricular, and intracisternal routes of injection. The toxin evoked vomiting after intravenous administration but not when given by the other routes. Ablation of the medullary emetic chemoreceptor trigger zone (CTZ) abolished the vomiting response. Intraventricular injection of tetrodotoxin, in doses from 1 250 to 1 500 of the intravenous requirement, caused volitional paralysis, hypothermia, and respiratory failure; pinna, corneal and deep tendon reflexes remained active. These effects are attributed to an action of the toxin on paraventricular brainstem structures since intracisternal injection failed to elicit any notable response. In acute experiments, respiratory failure due to intraventricular tetrodotoxin was characterized by loss of sensitivity to CO 2 and development of apneustic breathing; the medullary integrating mechanism continued to respond to stimulation after respiratory arrest.