RELATIONSHIP BETWEEN TRANSPORT OF GLUCOSE AND CATIONS ACROSS CELL MEMBRANES IN ISOLATED TISSUES .V. STIMULATING EFFECT OF OUABAIN, K+-FREE MEDIUM AND INSULIN ON EFFLUX OF 3-O-METHYLGLUCOSE FROM EPIDIDYMAL ADIPOSE TISSUE

1. 1. The permeability of adipocytes to a nonmetabolizable sugar was estimated by measuring the washout of 3-O-[14C]methylglucose from preloaded whole epididymal fat pads into a sugar-free environment. 2. 2. After an initial rapid phase, the release of 3-O-[14C]methylglucose was found to proceed with a rate coefficient of 0.0122 for up to 120 min. 3. 3. The release of 3-O-[14C]methylglucose was promptly stimulated by insulin (10-1000 μunits/ml) and inhibited by phlorizin (5 mM) and phloretin (1 mM). 4. 4. In a K+-free medium or in the presence of ouabain, the release of 3-O-[14C]methylglucose was gradually augmented, maximal effects being obtained after around 50 min. 5. 5. Other factors (2,4-dinitrophenol, CN-, epinephrine and ACTH), which could also be shown to reduce the K+ content of the tissue, stimulated 3-O-[14C]methylglucose release with a similar time-lag. © 1969.