Myo-inositol transport in slices of rat kidney cortex : I. Effect of incubation conditions and inhibitors

Abstract

The incubation conditions affecting the energy- and sodium ion-requiring uptake and retention of myo-inositol by slices of rat kidney cortex have been studied. No transport could be demonstrated in other tissues. Leakage of inositol from the slices amounted to 15% of the endogenous inositol in the first 45 min of incubation in air and at most to 8% on reincubation for 1 h in 95% O 2-5% CO 2. Removal of oxygen from the gas phase increased leakage and abolished the active uptake of inositol, effects which could not be prevented by the addition of energy sources such as glucose and ATP. The accumulation of radioactivity had a Q 10 greater than 3 and an apparent K m of 1.57·10 −4 M. A number of inhibitors of different stages of metabolic energy production interfered in varying degree with the uptake and retention of inositol. The extent of inhibition was largely determined by the concentration of the substance used, but an anomalous response was seen with 2,4-dinitrophenol. The results are discussed with reference to current concepts of active transport.