Oppositely directed actions of different doses of arginine-vasotocin and 1-deamino-arginine-vasotocin on sodium ion transport in skin of the frog Rana temporaria

Active transport of sodium ions across the isolated abdominal skin of the frog Rana temporaria after application of arginine-vasotocin (AVT) and 1-deamino-arginine-vasotocin (1dAVT) was studied by measurement of the short-circuit current (SCC). The maximal increase in the SCC values (26 and 19 mk/cm(2)) was observed after addition of 10 nM AVT or 100 nM 1dAVT, respectively, to the frog skin basal surface. An increase of concentration of AVT to 100 nM and of 1dAVT to 1 mu M terminated the sodium transport in the frog skin. A preliminary addition of an antagonist of arginine-vasopressin Vi(a)-receptors to the Ringer's solution at the frog skin basal surface led to a rise in the SCC values in response to administration of ineffective doses of AVT or 1dAVT. V-2-receptor antagonists did not affect the frog skin reaction to administration of these doses of AVT of 1dAVT.