RENAL FUNCTION IN MARINE TELEOSTS

IV. THE EXCRETION OF INORGANIC PHOSPHATE IN THE SCULPIN

¹ Front the Department of Anatomy, Harvard Medical School

1. When urine samples are taken at short intervals, the urinary phosphate concentration and excretion in the sculpin very often shows a moderate or marked, but transitory, increase. It is demonstrated that this transient increase is not an artifact due to phosphate precipitates in the bladder, ureter or collecting ducts.

2. By repeated catheterization the rate of endogenous phosphate excretion in the sculpin can be reduced to a low level, and any significant spontaneous increase in excretion can be suppressed.

3. It is shown, by a comparison of simultaneous xylose and phosphate clearances, that the glomerular kidney of the sculpin can under certain conditions excrete a urine with a phosphate concentration in excess of that which could be explained by glomerular filtration.

4. In line with Marshall and Grafflin's observations that the aglomerular kidney excretes phosphate that is derived from some unidentified precursor (other than inorganic phosphate in the plasma), the present observations establish the presumption that a similar process occurs in the glomerular kidney of the sculpin.

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