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. 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. 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. 3. Heat treatment of GV did not decrease activity, while heating SV reduced it. 4. 4. In-vivo experiments showed mainly a depressor response in rat and guinea-pig.