THE CARDIAC EFFECTS OF NEUROHYPOPHYSEAL HORMONES IN THE EEL, ANGUILLA-JAPONICA (TEMMINCK AND SCHLEGEL)

The cardiac effects of neurohypophysial hormones in the Japanese eel, Anguilla japonica (Temminck and Schlegel), were studied in isolated atrial preparations at room temperatures of 17-20°C, 25-28°C, or 28°C. Arginine vasotocin (AVT), oxytocin (OXY), mesotocin (MSN), and isotocin (ISN) produced dose-related positive chronotropic and inotropic responses. Arginine vasopressin (AVP) was not effective. The effects of ISN on the atrial rate and tension were not affected in the presence of phentolamine or propranolol, which are α and β adrenergic antagonists, respectively. The activity of the eel heart and the effects of neurohypophysial hormones are temperature-dependent. The functional significance of these cardiac effects of neurohypophysial hormones is not known. © 1990 Springer-Verlag.