Effects of arginine vasotocin, cortisol and adrenergic factors on water balance in the toad Bufo bufo: physiology or pharmacology?

Abstract

1. The threshold level of exogenous arginine vasotocin (AVT) for increasing the cutaneous water permeability in Bufo bufo was several times higher than has been measured in dehydrated frogs and toads. 2. The beta-agonist isoproterenol was without effect on water balance in hydrated toads but increased the response to large doses of AVT by 25-50%. 3. Implantation of cortisol pellets in water-acclimated toads enhanced the cutaneous water permeability by a factor of 2-3. 4. It is concluded that understanding of water balance in terrestrial anurans may depend upon the unravelling of mechanisms that integrate cutaneous water transport and diuresis.