Vascular responses elicited by venom of Arabian catfish (Arius thallasinus)

The Arabian catfish produces venoms from the skin (SV) and glands near the pectoral spines (GV). 1. The venoms have a high protein concentration, only limited amounts of lipid, carbohydrate and nucleic acid. Enzyme activities included alkaline phosphatase and esterases. Both SV and GV induce hemolysis. 2. SV and GV induced a dose-dependent smooth muscle contraction of human umbilical artery preparations. This response was competitively inhibited by atropine, suggesting a cholinergic response. 3. Heat treatment of GV did not decrease activity, while heating SV reduced it. 4. In-vivo experiments showed mainly a depressor response in rat and guinea-pig.