Potassium in proximal tubule fluid of rats and Necturus measured with glass electrodes.

Abstract

The concentration of potassium in proximal tubule fluid of both rat and Necturus was measured using potassium-sensitive glass microelectrodes. The potassium TF/P [tubular fluid/plasma] ratio found in Necturus was 1.9 - 0.2 (SE) [standard error] while that in the rat was 0.7 [plus or minus] 0.08. These values agree with the majority of results published previously. Since the potassium concentration in fluid obtained from rat and Necturus was measured with identical techniques, it is apparent that the differences in tubule fluid potassium concentration of the 2 species do not merely reflect method -ologic differences in analysis but represent distinct differences in the transport of potassium in the proximal tubule of rat and Necturus.