The effects of neurohypophysial hormones on the vascular resistance of the isolated perfused gill of the European eel, Anguilla anguilla L.

Arginine vasotocin (AVT) and oxytocin (OXY), in the dose range of 2 X 10(-13)-2 X 10(-8) mol, were found to be potent vasoconstrictors of the arterioarterial pathway of isolated perfused eel gills. AVT was significantly (P less than 0.05) more potent than OXY, as indicated by the results of both dose- and concentration-response curves. Isotocin (IT) and arginine vasopressin (AVP) were unable to elicit a vascular response at doses of up to 2 X 10(-8) mol. The arteriovenous component of branchial flow was not affected by these four peptides. Results from constant-pressure head and constant-flow preparations yielded similar results.