FFA CONCENTRATION DID NOT AFFECT CARBOHYDRATE METABOLISM IN SOLEUS MUSCLE IN VITRO.

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1407 The increased FFA availability during fasting and exercise is viewed as an evidence of casual relation with its carbohydrate sparing effect. In order to verify the effect of FFA availability within physiological range on carbohydrate metabolism and its interrelation with exercise and fasting, swimming trained ( T) and sedentary ( S) rats were subdivided into control ( A - fed ad lib) and 48 h fasted( F) groups. Strips of soleus muscles were obtained after a single swimming bout, and incubated in Krebs-Ringer buffer (glucose 5.5 mM, insulin 100 um/mL) with addition of oleate at 0.4 or 0.8 mM. Glucose uptake(1-3H-2.DG) was not affected by fasting but increased by training( SA: 37.5±2.5, SF: 37.7±3.0, TA: 38.8±1.8, TF: 38.4±2.3 μmol.g-1.h-1). Incorporation of U-14C-glucose into glycogen was lowered by fasting, and in fed state, the training decreased it ( SA: 5.3±0.8, SF: 5.6±0.3, TA: 3.0±0.4, TF: 4.2±0.5 μmol.g-1.h-1). Training decreased the lactate production from 14C glucose ( SA: 8.8±1.6, SF: 9.5±1.2, TA: 7.7±1.2, TF: 8.3±1.0 μmol.g-1.h-1) but increased the total lactate production ( SA: 12.9±0.8, SF: 15.3±1.4, TA: 26.2±2.9, TF: 20.9±2.9μmol.g-1.h-1). The increase in FFA content in the incubation medium from 0.4 to 0.8 mM did not affect any result. These results suggest that the cellular state is more powerful factor to spare carbohydrate than FFA availability.