TESTOSTERONE AND SUGAR TRANSPORT IN LEVATOR ANI MUSCLE OF RAT

1. 1. The effect of testosterone on xylose transport kinetics in levator ani muscle of sexually immature rat has been studied and compared with those effects of other experimental conditions responsible for changes in penetration of sugar into striated muscle fibers. 2. 2. Testosterone increases the penetration rate of xylose by stimulation of transport mechanisms. This is inhibited by phlorizin. No changes in the penetration of l-glucose take place. 3. 3. Kinetic analysis shows that increased penetration rates are attributable to a considerable increase in vmax; Km values remain substantially unchanged. 4. 4. Such increased penetration rates are not additive to those of insulin, anaerobiosis, direct stimulation and cyanide. 5. 5. The effect of testosterone on penetration of sugar is not dependent on pancreatic, adrenal or hypophyseal secretions. However, acute denervation of the muscle completely blocks action of testosterone. © 1969.