Effect of exercise on the plasma nonesterified fatty acid composition of dogs and goats: Species with different aerobic capacities and diets |
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Authors: | Grant McClelland Georges Zwingelstein C Richard Taylor Jean-Michel Weber |
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Affiliation: | (1) Institut Michel Pacha, Université de Lyon, 83500 La Seyne sur Mer, France;(2) Concord Field Station, Museum of Comparative Zoology, Harvard University, 02138 Cambridge, Massachusetts;(3) Biology Department, University of Ottawa, 30 Marie Curie, K1N 6N5 Ottawa, Ontario, Canada;(4) Present address: Department of Zoology, University of British Columbia, 6270 University Blvd., V6T 1Z4 Vancouver, B.C., Canada |
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Abstract: | The goals of this study were to determine: (i) whether mammals mobilize particular nonesterified fatty acids (NEFA) preferentially
during locomotion, (ii) if differences in aerobic capacity or diet can affect the pattern of NEFA mobilization and (iii) which
individual NEFA are most representative of total NEFA concentration changes, to use them as tracers for turnover studies.
Individual NEFA were measured in trained dogs and goats (VO2max dog/VO2max goat=2.2; where VO2max=max-imal oxygen consumption) during treadmill exercise at 40 and 60% VO2max. Important interspecies differences in individual NEFA concentrations could be attributed to differences in aerobic capacity.
The more aerobic species (dog) had much higher plasma NEFA concentrations for all but one NEFA (18∶0), when compared with
the low-aerobic species (goat). In addition, exercise caused a large increase in concentration of individual NEFA in the dogs,
with the largest increases seen in 18∶1 (150% above resting values) and 16∶0 (60% increase), but it had no effect in goats.
Therefore, the aerobic species has a much higher ability for mobilizing and transporting NEFA in plasma than its low-aerobic
counterpart. Two NEFA accounted for more than half total plasma NEFA in both species, 18∶1 (about 35% total NEFA) and 16∶0
(20%). Calculation of variability in percent composition reveals that oleate and palmitate also closely reflect changes in
total NEFA and are therefore the most appropriate tracers forin vivo kinetic studies in exercising mammals. Differences in diet and digestion physiology explained some differences in the plasma
NEFA composition of the two species; this was reflected in the percent contributions of individual fatty acids to total NEFA:
in dogs 18∶1>16∶0>18∶2>18∶0, while in goats 18∶1>16∶0>18∶0>18∶2. Also, only goats had 18∶3 (6% total NEFA), a fatty acid of
plant origin, while only dogs had 16∶1 (7% total NEFA). Overall, however, the plasma NEFA composition of goats did not exactly
reflect that of their diet due to preabsorptive modification of unsaturated fatty acids, while in dogs there was a good correlation
between dietary and plasma NEFA. |
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