Figure 9.

Early-life Na depletion programs increased basal metabolic rate via increased autonomic activity. A and B: fat-free mass (FFM; A) and fat mass (B) of mice at 8 wk of age. C: basal metabolic rate (BMR) before and after acute injection of hexamethonium (30 mg/kg ip). For A–C, n = 8 for each group and data presented as mean ± SE. A and B analyzed by 2-tailed independent t test, and C analyzed by 2-way ANOVA, followed by Šídák's multiple comparisons test (*P < 0.05). D: comparison of relative contributions of activity-dependent energy expenditure, the thermic effect of food (TEF) plus adaptive thermogenesis (AT), and basal metabolic rate to total energy expenditure. Fractional contributions estimated with week 9 energy expenditure data from male mice studied in Promethion [with ad libitum food access at room temperature (22°C)] as shown in Figs. 7 and 8, plus basal metabolic rate from fasted 8-wk-old males studied at thermoneutrality (30°C) as shown in C.