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Nonnutritive flow impairs uptake of fatty acids by white muscles of the perfused rat hindlimb
journal contributionposted on 2023-05-16, 14:26 authored by Clerk, LH, Smith, ME, Stephen RattiganStephen Rattigan, Michael ClarkMichael Clark
Triglyceride hydrolysis by the perfused rat hindlimb is enhanced with serotonin-induced nonnutritive flow (NNF) and may be due to the presence of nonnutritive route-associated connective tissue fat cells. Here, we assess whether NNF influences muscle uptake of 0.55 mM palmitate in the perfused hindlimb. Comparisons were made with insulin-mediated glucose uptake. NNF induced during 60 nM insulin infusion inhibited hindlimb oxygen uptake from 22.0 Â± 0.5 to 9.7 Â± 0.8 Î¼molÂ·g-1Â·h-1 (P < 0.001), 1-methylxanthine metabolism (indicator of nutritive flow) from 5.8 Â± 0.4 to 3.8 Â± 0.4 nmolÂ·min-1Â·g-1 (P = 0.004), glucose uptake from 29.2 Â± 1.7 to 23.1 Â± 1.8 Î¼molÂ·g-1Â·h-1 (P = 0.005) and muscle 2-deoxy-glucose uptake from 82.1 Â± 4.6 to 41.6 Â± 6.7 Î¼molÂ·g-1Â·h-1 (P < 0.001). Palmitate uptake, unaffected by insulin alone, was inhibited by NNF in extensor digitorum longus, white gastrocnemius, and tibialis anterior muscles; average inhibition was from 13.9 Â± 1.2 to 6.9 Â± 1.4 Î¼molÂ·g-1Â·h-1 (P = 0.02). Thus NNF impairs both fatty acid and glucose uptake by muscle by restricting flow to myocytes but, as shown previously, favors triglyceride hydrolysis and uptake into nearby connective tissue fat cells. The findings have implications for lipid partitioning in limb muscles between myocytes and attendant adipocytes.
Publication titleAmerican Journal of Physiology: Endocrinology and Metabolism
Department/SchoolTasmanian School of Medicine
PublisherAmerican Physiological Society
Place of publicationBethesda, USA