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The role of the urinary bladder in salt and water metabolism of the toad, Bufo marinus

1968; Pergamon Press; Volume: 26; Issue: 1 Linguagem: Inglês

10.1016/0010-406x(68)90312-5

1879-3029

Stewart A. Middler, Charles R. Kleeman, Eleanor Edwards,

Bat Biology and Ecology Studies

1. When Bufo marinus toads are kept out of water until they lose 7–12 per cent of their body weights the ratio of bladder urine to plasma osmolality approaches isotonicity (Uosm/Posm= 1·0). 2. Ureteral urine of toads under similar conditions of water deprivation is typically dilute, even when the animals are oliguric (urine flow of 0·3–4·0 ml/kg per hr. 3. The excretion of sodium by the kidney per se (uninfluenced by bladder function) is correlated with the salinity of the medium varying between about 15 μequiv./kg per hr to 1500 μequiv./kg per hr when the medium is distilled water or 100 mequiv./1. NaCl respectively. 4. Adaptation to high salt (100 mequiv./l.) as compared to 10 mequiv./l. NaCl significantly reduces ureteral urine flow, Na+ concentration and Na+ excretion. 5. Adaptation to distilled water significantly decreases Na+ concentration and excretion in ureteral urine, when compared to toads adapted to 10 mequiv./ l. NaCl. 6. The ureteral urine of salt-restricted toads has a Na+ concentration 10–12 times greater than bladder urine under similar conditions. 7. The resorption of Na+ from the intact urinary bladder has been demonstrated. 8. All of the urine formed by the kidneys enters the urinary bladder under conditions of hydration.