Prostaglandin associated mortality following intravenous injection of catfish epidermal secretions in rabbits

Toxicity of soluble protein extracts from epidermal gel secretions of the catfish, $\text{Arius thalassinus}$, was examined in rabbits. Intravenous injections containing doses as low as 2 mg protein/kg body weight caused mortality in all animals tested. An increase in plasma levels of thromboxane B₂ (TXB₂) and of 6-keto prostaglandin F_1α (6-keto PGF_1α) were observed following injections. Both the mortality and prostaglandin release were prevented by pretreatment of rabbits with either indomethacin or hydrocortisone. A similar indomethacin sensitive induction of prostaglandin release was noted following the $\text{in vitro}$ treatment of arterial tissue sections with gel. Lethality appears to result from gel substances stimulating phospholipase activity to yield arachidonic acid, which is then metabolized to give toxic levels of prostaglandins.