Table 2.

Metabolic and activity measures in young and old B6D2F1 mice (n = 5–13/group)

		Young	Old
Body mass (g)		38.0 ± 1.0	36.2 ± 1.2
(ml kg−1 h−1)	Night	2797 ± 96	2685 ± 58
	Day	2766 ± 96	2408 ± 145
(ml kg−1 h−1)	Night	2346 ± 58	2352 ± 185
	Day	2295 ± 79	2086 ± 152
RER	Night	0.84 ± 0.02	0.87 ± 0.01
	Day	0.83 ±0.02	0.86 ± 0.02
Heat (kcal h−1)	Night	0.52 ± 0.02	0.48 ± 0.04
	Day	0.51 ± 0.02	0.43 ± 0.04
Food intake (g day−1)	Night	5.4 ± 0.3	7.3 ± 0.6*
	Day	6.5 ± 0.4	8.9 ± 0.8
Water intake (ml day−1)	Night	4.4 ± 0.5	7.4 ± 1.2*
	Day	5.2 ± 0.4	9.2 ± 2.4
Activity (beam breaks day–1)	Night	1041 ± 196	976 ± 139
	Day	907 ± 156	651 ± 256
Fasted blood glucose (mg dl−1)		124 ± 3	120 ± 4
Fasted plasma insulin (ng ml−1)		1.3 ± 0.1	2.4 ± 0.4*
HOMA-IR%		4.6 ± 0.4	7.1 ± 0.3*
HOMA-B%		117 ± 8	184 ± 26*
AUC-GTT (mg dl−1 min–1)		12557 ± 316	14956 ± 1033*
Plasma FFA (μmol)	Fasted	312 ± 33	347 ± 58
	Fed	726 ± 59	967 ± 150

P < 0.05, means ± s.e.m. Abbreviations: AUC-GTT, area under the curve for glucose during glucose tolerance test; FFA, free fatty acids; HOMA-B%, homeostatic model assessment of beta cell function; HOMA-IR%, homeostatic model assessment of insulin resistance; RER, respiratory exchange ratio; , carbon dioxide production; , oxygen consumption.

^*Denotes difference from young.