Figure 4. Zinc-deficient mice have lower zinc plasma concentration with no significant baseline differences in injury, inflammation, respiratory mechanics, or body weight.

(A) C57BL/6 mice were fed a standard diet (control, Picolab, 5058, 120 ppm Zn) or a zinc-deficient diet (Zn def, Harlan Teklad, TD85419; 1 ppm Zn) for 3 weeks. Plasma was collected and assessed for zinc levels. Plasma zinc levels in the zinc-deficient mice were significantly reduced in comparison with control mice, n = 4/group, data presented as mean ± SEM. *P < 0.05 by Mann-Whitney t test (nonparametric 2-tailed t test). (B) Control and zinc-deficient mouse lungs were fixed at 30 cmH₂0, paraffin embedded, and then stained with H&E. Original magnification, ×200. Lungs from both groups were normal in appearance. (C) Control and zinc-deficient lung tissue homogenates (n = 3/group) were assayed for a panel of inflammatory cytokines by multiplex ELISA (nd denotes levels of cytokine were not detectable in sample). No significant differences were found between the groups. (D) Respiratory mechanics were assessed at baseline using the Flexivent mouse ventilator in zinc-deficient and control mice. No difference was found in tissue elastance between the groups; n = 9 in control and 7 in zinc-deficient group, data presented as mean ± SEM. (E) Body weights were measured in zinc-deficient and control mice after 3 weeks on a zinc-deficient or control diet before performing mechanical ventilation or LPS exposure experiments. No significant differences were found between the groups; n = 10 in control and 7 in zinc-deficient group, data presented as mean ± SEM.