Creatinine Secretion by the Frog Renal Tubule

¹ From the Department of Physiology, University of Minnesota, Minneapolis, Minnesota

Simultaneous creatinine and inulin clearance measurements were carried out in Ringer-perfused and intact kidneys of the bullfrog (R. catesbiana). For the perfusion series the median creatinine/inulin clearance ratio was 1.27. The ratio was elevated above unity for the majority of intact kidney experiments. Perfusion with poisons such as phlorizin, sodium azide, sodium arsenite and 2, 4-dinitrophenol, as well as elevation of the creatinine concentration in perfusing fluids, generally depressed the clearance ratio toward unity. It is concluded that a portion of the urinary creatinine of bullfrogs can be excreted by active tubular participation.

Note:
with the technical assistance of Lucille Ryan Gravelle