Meeting Abstract
63.1 Sunday, Jan. 5 13:30 Cold and Exercise Training Produce Similar Increases in Maximal Metabolic Output in House Sparrows ZHANG, Y.*; SWANSON, D. L.; University of South Dakota; University of South Dakota yufeng.zhang@usd.edu
Maximal metabolic output for both exercise and thermogenesis in birds presumably influence fitness through effects on flight and shivering performance. Because both summit (Msum = maximum thermoregulatory metabolic rate) and maximum (MMR = maximum exercise metabolic rate) metabolic rates are functions of skeletal muscle, correlations between these measurement might occur, but this has been little studied in birds. We measured effects of 3-week experimental cold and exercise training protocols on body (Mb) and muscle masses, basal metabolic rate (BMR), Msum, MMR, and citrate synthase (CS), β-hydroxyacyl CoA-dehydrogenase (HOAD) and carnitine palmitoryl transferase (CPT) activities in house sparrows (Passer domesticus ). Both training protocols resulted in significantly higher Msum, MMR, Mb, CPT and CS activities in pectoralis (PEC) with non-significant trends toward higher CPT and CS activities in supracoracoideus than in the control group. Exercise-training also significantly increased PEC and heart masses and cold-training also produced a nearly significant increase in PEC mass (P=0.058). BMR showed a trend (P=0.087) toward increasing with cold training, but BMR was significantly reduced by exercise training. These data indicate that both cold and exercise training modified the phenotype of house sparrows to similarly increase maximal metabolic outputs for exercise and thermogenesis. These increases are associated with increases in Mb, PEC and heart masses, and enzyme activities in both groups, suggesting that such changes are prominent drivers of metabolic flexibility. Correlation between the two measures of maximal metabolic output indicate that cross-training effects between cold and exercise may occur for birds. However, BMR varied differently with exercise and cold training, suggesting that other factors (e.g., changes in digestive organs) account for flexibility in BMR.
