Theaaction of neurohypophysial and adrenocortical hormones on sodium balance in the cyclostome, Lampetra fluviatilis

Abstract

The effect of neurohypophysial and adrenocortical hormones on the rate of net sodium loss from the lamprey ( Lampetra fluviatilis) was investigated. Neurohypophysial hormones increased the rate of sodium loss. Oxytocin on a unit weight basis was approximately five times as effective as Pitressin, arginine vasotocin or 3-valine oxytocin. The oxytocin-like polypeptide present in teleost neurohypophyses also increased the rate of sodium loss. Aldosterone and ACTH decreased the rate of sodium loss. The aldosterone blocking agent SC 11927 increased it. Cortisol had no effect. The results are discussed in relation to the electrolyte metabolism of lampreys and to vertebrate phylogeny generally.