GLUCOSE REABSORPTION IN RAT KIDNEY MICROPUNCTURE ANALYSIS OF TUBULAR GLUCOSE CONCENTRATION DURING FREE FLOW

Glucose concentration was determined enzymatically in tubular fluid samples taken during free-flow micropuncture along the length of the proximal convolution in anaesthetized rats. The glucose concentration decreased exponentially in the first half of the proximal convolution to a mean value of 0.9 mM/l, and did not change in the remaining length accessible to micropuncture. An identical mean value was found in the final urine. When the rates of salt and water reabsorption were varied experimentally, calculated glucose reabsorption showed no relationship to tubular length measured from glomerulum to puncture site. It appears, therefore, that in addition to the mass of reabsorptive tissue and the glucose concentration of tubular fluid, the reabsorption of water and electrolytes plays an important part in determining the rate of glucose reabsorption by the kidney. © 1968 Springer-Verlag.