Skeletal muscle-specific Nampt ablation results in reduced growth and premature death.A) NAMPT protein levels in gastrocnemius muscle of male WT and SMNKO mice (9–14 weeks of age, n = 8–13). B and C) NAD+ and NADH levels in gastrocnemius muscle of male WT and SMNKO mice (9–14 weeks of age, n = 8–13). D and E) NADP+ and NADPH levels in gastrocnemius muscle of male WT and SMNKO mice (9–14 weeks of age, n = 8–13). F and G) Bodyweight measurements in (F) male and (G) female mice (n = 9–40). H and I) Lean and fat mass measurements in WT and SMNKO male mice (n = 9–40). J) Body fat percentage in WT and SMNKO male mice (n = 9–40). K) Representative CT scan of a WT and an SMNKO mouse at 5 weeks of age, displaying spinal cord deformities and kyphosis. L) Survival curves of WT (n = 102) and SMNKO (n = 40) mice. M and N) Twitch force traces (M) and max force (N) in soleus of WT and SMNKO mice (6 weeks of age, n = 8). O and P) Twitch force development (O) and decay (P) in soleus of WT and SMNKO mice (6 weeks of age, n = 8). Q) Tetanic force measured as area under the curve (AUC) in soleus of WT and SMNKO mice (6 weeks of age, n = 8). Error bars represent SEM. ∗ Difference to WT control of the same age. # Main effect of genotype.