DEFECT IN REGULATION OF MEMBRANE-TRANSPORT OF MONOSACCHARIDES IN DYSTROPHIC MUSCLE

The penetration of a nonmetabolized glucose analogue, 3-O-methyl-D-glucose, across the plasma membranes of tissues from dystrophic mice and cardiomyopathic (dystrophic) hamsters has been compared with that of normal controls. Under basal conditions the penetration of test sugar was similar in lens and diaphragm of normal and dystrophic 129/ReJ mice. Stimulation of sugar transport by 2,4-dinitrophenol did occur in normal but not in dystrophic diaphragm. A submaximal concentration of insulin had a more variable effect in dystrophic than in normal muscle while a supramaximal concentration of the hormone increased the uptake of the glucose analogue to an equal extent in the two tissues. In the BIO 14.6 strain of cardiomyopathic hamsters, uncoupling of oxidative phosphorylation did not increase sugar transport in extensor digitorum longus muscles, while the normal effect was observed dystrophic dystropic soleus and in both these muscles of the random bred controls. The absence of an effect by a condition simulating anoxia suggests that in dystrophy, certain muscles are unable to accelerate the entry of glucose when this is required.