Salt and water balance in the desert iguana,Dipsosaurus dorsalis

Summary Adult desert iguanas were either injected IM with aldosterone or lizard physiological saline (Ringers). These pairs according to group were left intact, adrenalectomized, or sham-adrenalectomized. Some groups of operated lizards were loaded IP with either NaCl or KCl. Aldosterone markedly reduced sodium output by the nasal salt gland during these experiments whereas Ringers did not. Nasal and urine K output of those lizards treated with aldosterone did not differ from that of their respective controls. The K/Na ratio of both the nasal fluid and urine increased only in the aldosterone treated lizards. The effect of aldosterone on the wet weight, dry weight, or proportion of water in the urine, or on precise changes of sodium and potassium levels therein was obscured by the complex traumatic effects of experimentation on the formation and voiding of urine.Bilateral adrenalectomy markedly elevated nasal sodium output in the controls. Adrenalectomized lizards treated with aldosterone, however, reduced nasal sodium output even if loaded with NaCl. The pattern of nasal K excretion resembled those of the controls.This study was supported in part by grant GB-3010 from the U.S. National Science Foundation.