Cold Stress Increases Lipolysis, FFA Ra and TG/FFA Cycling in Humans

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Authors
  1. Vallerand, A.L.
  2. Zamecnik, J.
  3. Jones, P.
  4. Jacobs, I.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
Abstract
To characterize the important changes in the selection and mobilization of metabolic fuel during cold stress, six males rested for 3 h at 29C and at 5C dressed only in shorts whil 2H5 glycerol, 113(-)C palmitate and 6,6 2H5 glucose were continuously infused for 3 h in each condition to determine their rate of turnover (Ra). Metabolic rate (M) as well as rates of carbohydrate (CHOox) and lipid oxidation (FATox) were assessed by indirect calorimetry whereas all isotopic enrichments were determined by mass spectrometry. Cold exposure decreased rectal and mean skin temperatures and increased M. FATox and CHOox compared with the same test all thermal neutrality (p<0.05). As expected, cold increased plasma glucose Ra and plasma FFA Ra (from 4.58 + or - 0.19 to 14.69 + or - 1.07 mumol-kg1(-)-min1(-);p<0.05). However, in absolute terms, plasma FFA Ra in the cold remained more than twice greater than FATox (FATox only increased up to 6.9 + or - 0.85 mumol-kg1(-)-min1(-)), suggesting an enhanced non-oxidative disposal of fatty acids (i.e., TG/FFA cycling) to account for all FFA Ra. Indeed, cold increased extracellular TG/FFA recycling rate (2.23 + or - 0.40 vs 7.77 + or - 1.19 mumol-kg1(-)-min1(-): p<0.05) whereas intracellular cycling was unaffected. TRUNCATED
Keywords
Energy metabolism;Energy substrates;Glycerol;Heat balance;Heat production;Non-oxidative disposal;Stable isotope
Report Number
DCIEM-98-P-04 — Reprint
Date of publication
08 Sep 1999
Number of Pages
12
Reprinted from
Aviation, Space, and Environmental Medicine, vol 70, no 1, 1999, p 42-50
DSTKIM No
99-01455
CANDIS No
511496
Format(s):
Hardcopy;Document Image stored on Optical Disk

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