Absorption of water and electrolytes from the cloaca of an Australian lizard, Varanus gouldii (gray)

Abstract

1. 1. An isotonic solution was introduced in vivo into the isolated cloaca of V. gouldii. Changes in the volume and composition of the fluid were measured. 2. 2. Fluid was absorbed from the cloaca of V. gouldii at a rate of 8·± 0·6 ml/kg per hr at 30°C. 3. 3. AVT (arginine vasotocin) increased the rate of absorption by increasing the permeability to water and the rate of sodium transport. 4. 4. Secretion of potassium into the cloaca was found in some of the control animals. 5. 5. The resorption of fluid from the urine is essential to derive the full benefits of water conservation that are associated with uricotelism.