Effects of exogenous somatostatin and antisomatostatin on serum parameters of the American eel

1. Bolus injections of a wide range of concns. of somatostatin and of antisomatostatin, in cardiac-cannulated eels had no specific effects on serum osmolality, sodium, potassium and chloride. 2. A presumably physiological dose of somatostatin had a pronounced and sustained hyperglycemic effect beginning 160 min after the injection, which was absent at higher doses. However, an extremely high dose caused an early, temporary hyperglycemia. 3. Antisomatostatin also caused a hyperglycemia, which appeared after 20 min and lasted less than 24 hr. 4. It appears that, in the freshwater eel, somatostatin affects both hyper- and hypoglycemic mechanisms and that these effects depend on its concn and/or site of action.