Diaphragm-specific force generation in response to phrenic nerve stimulation as a function of phrenic nerve stimulation frequency. Group mean data ±1 SE are shown for sham controls (black) and cecal ligation puncture (CLP) sepsis (red)-, sham+SS31 (green)-, and CLP+SS31 (blue)-treated groups (n = 5–6 mice per group). Phrenic nerve-stimulated diaphragm force generation was similar to that observed in response to direct muscle stimulation, with diaphragm force generation in response to sepsis markedly reduced compared with sham controls (P < 0.01 at 1 Hz, P < 0.001 at 20 and 50 Hz for comparison of these 2 groups). SS31 prevented sepsis-induced reductions in diaphragm force assessed in response to phrenic nerve stimulation, with force for CLP+SS31 significantly higher than that for CLP for each stimulation frequency (P < 0.02 at 1 Hz, P < 0.001 at 20 and 50 Hz). Phrenic nerve-stimulated diaphragm force generation for sham+SS31 was similar to that for sham controls (not significant). *Statistical significance.