Octanoate oxidation measured by¹³C-NMR spectroscopy in rat skeletal muscle, heart, and liver

Abstract

Contribution of octanoate to the oxidative metabolism of the major sites of fatty acid oxidation (heart, liver, and resting and contracting skeletal muscle) was assessed in the intact rat with 13C-NMR spectroscopy. Under inhalation anesthesia, [2,4,6,8-13C4]octanoate was infused into the jugular vein and the sciatic nerve of one limb was stimulated for 1 h. Octanoate was a principal contributor to the acetyl-CoA pool in all tissues examined, with highest oxidation occurring in heart and soleus muscle followed by predominantly red portion of gastrocnemius muscle (RG), liver, and then white portion of gastrocnemius muscle (WG). Fractional contribution of 13C-labeled octanoate to the acetyl-CoA pool (Fc2) was 0.563 +/- 0.066 for heart and 0.367 +/- 0.054 for liver. Significant differences were observed between each of the muscle types during both rest and contraction. In muscle, Fc2 was highest in soleus (0.565 +/- 0.089 rested, 0.564 +/- 0.096 contracted), followed by RG (0.470 +/- 0.092 rested, 0.438 +/- 0.072 contracted), and lowest in WG (0.340 +/- 0.081 rested, 0.272 +/- 0.065 contracted). Our findings demonstrate that the fractional contribution of octanoate to oxidative metabolism correlates with oxidative capacity of the tissue and that octanoate metabolism increases in contracted muscle in proportion to the overall increase in oxidative rate.

Priority use of medium-chain fatty acids during high-intensity exercise in cross-country skiers

“…Octanoate (C10:0) contributes 50% of the acetyl-CoA pool in the heart and soleus muscle under normal physiological conditions. Octanoate metabolism increases in contracted muscle proportional to the overall increase in the oxidative rate [ 28 ]. However, further discussions would be speculative.…”

Differential effects of thyroid hormones on energy metabolism of rat slow‐ and fast‐twitch muscles

“…Increased muscle expression of UCP3 following TH stimulation may contribute to an increased basal metabolic rate, due to mitochondrial uncoupling (de Lange et al, 2001; Lebon et al, 2001). However, other uncoupling mechanisms could also be involved, such as T3 induced changes in the phospholipid composition of mitochondria (Walton et al, 2003).…”

Evaluation of the 13C-Octanoate Breath Test as a Surrogate Marker of Liver Damage in Animal Models

“…5 Comparison of MBID parameters between BDL and sham-operated rats (*P B 0.05) that this is maintained mainly by extrahepatic sites of fatty acid oxidation [17]. Indeed, it is possible that the described changes in the shape of OBT curves in different stages of experimental cirrhosis reflect, at least partially, the extrahepatic oxidation of octanoate in the heart, muscles, and kidney, as has been described in both humans and rats [28,29]. This observation may also be related to the effect of changes in hepatic blood flow on the pharmacokinetics of octanoate.…”