Table 2.

Diaphragm muscle contractile properties across the lifespan in mice (6, 18 and 24 months)

				P (two-way ANOVA)
	Control	BDNF	1NMPP1	Age effect	Treatment effect	Interaction
Pt (N cm−2)				<0.001	0.015	0.759
6 months	6.1 ± 0.5	6.0 ± 0.3	5.3 ± 0.3
18 months	5.8 ± 0.2	5.6 ± 0.2	4.9 ± 0.3
24 months	4.7 ± 0.3*	3.9 ± 0.4*	3.8 ± 0.4*
Po (N cm−2)				<0.001	0.897	0.412
6 months	18.8 ± 1.0	19.7 ± 1.1	19.5 ± 1.1
18 months	18.6 ± 0.8	18.8 ± 0.6	17.5 ± 0.7
24 months	14.7 ± 0.3*	12.9 ± 1.0*	14.5 ± 1.0*

Maximal twitch force (P_t) and isometric tetanic force (P_o) are normalized to physiological cross-sectional area (mean ± SEM). Data were obtained using diaphragm muscle–phrenic nerve preparations in control, or BDNF-or 1NMPP1-treated groups (n = 7–9 per group) prior to neuromuscular transmission failure testing. Diaphragm muscle contractile properties were assessed only with direct muscle stimulation and were thus independent of the data presented in Fig. 1, but were necessary to verify preparation quality and possible effects of treatment. Post hoc comparisons show both P_t and P_o at 24 months significantly different from at 6 and 18 months(^*) and P_t in the control is significantly different from in the 1NMPP1 treatment group.