URINE PRODUCTION AND URINATION IN THE PLAICE PLEURONECTES-PLATESSA

1. 1. The clearance of radioactively labelled sulphate by the plaice has been investigated after intraperitoneal injection. 2. 2. Labelled sulphate release is acutely episodic, and such episodes are identified with urination because of the accumulation of sulphate and of label observed in the bladders of fish where such a release was not observed during the time of observation. 3. 3. Urine production is slow and spontaneous urination is an infrequent occurrence; eight were observed in a total of 44 fish days of observation. 4. 4. The frequency of urination is not measurably affected by handling stress. 5. 5. Average urine output is estimated to be 0.08 ml/kg/hr or less. 6. 6. Analyses of plasma, urine and rectal fluid are presented. 7. 7. The validity of urine flow rates and analyses by the technique of cannulating the urinary papilla is discussed. © 1990.