An in vitro muscle strip incubation system was developed to measure the rate of catabolism of 1 mmol/L [1-14C]octanoate, 1 mmol/L... » More

An in vitro muscle strip incubation system was developed to measure the rate of catabolism of 1 mmol/L [1-14C]octanoate, 1 mmol/L [1-14C]nonanoate, 1mmol/L [9-14C]nonanoate and 10 mmol/L [U-14C]glucose by measuring the recovery of 14CO2. Muscle strips (13 mm?1.5 mm ~50 mg) were isolated from triceps brachii and gracilis muscles of newborn and 2 d old, small (<950 g) and large (>1450 g) piglets. The position of the 14C label in the substrate affected the rate and amount of recovery in 14CO2. Therefore, comparisons were made between age groups (0 vs 2 d) within substrates but limited across substrates to comparisons of [1-14C] labeled fatty acids. Substrate oxidation rates did not differ in muscle strips from small and large piglets (P > 0.99) or in strips isolated from the triceps and gracilis muscles (P > 0.08), nor were interactions involving pig weight or muscle type significant, therefore results were pooled across these factors. Over the first two days of life, medium chain fatty acid oxidation [pmol/(h?mg muscle strip)] increased (P<0.05) 50-80% , but the 20% decrease in glucose oxidation was not significant (P > 0.05). By day 2, the oxidation rate of nonanoate as represented by the one carbon, was 25% greater than for octanoate (P< 0.005). The conversion of [9-14C]nonanoate to 14CO2 indicated muscle had the capacity to oxidize the propionyl CoA produced by ß-oxidation of nonanoate and that odd chain C-9 medium chain fatty acid provided anabolic carbon to the citric acid cycle.

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