FIGURE 6.

Acid-base status of KO_b/c mice during 3-day MAc-challenge. pCO₂ (A,B), plasma pH (C,D), and [HCO₃ ⁻] (E,F), were measured in unanesthetized animals the day before (timepoint “0”) and each day of a 3-day MAc-challenge (timepoints “1–3”). Panels A, C, and E show the averaged parameter values, and panels B, D, and F show the average % change from baseline, for each genotype after each day of the 3-day MAc-challenge. (A) pCO₂. At baseline, KO_b/c mice had a significantly lower pCO₂ than WT mice (timepoint 0) but there were no significant differences during MAc (timepoints 1–3). (B) When normalized to baseline, WT mice exhibited a significant % change in pCO₂ in response to MAc (p = 0.011, RM-ANOVA) that was not observed in KO_b/c mice (p = 0.889, RM-ANOVA). Furthermore, the % decrease in pCO₂ in WT mice after 1 day of MAc was significantly different from the % change in KO_b/c mice (timepoint 1). (C) Plasma pH. There were no significant differences between the plasma pH of WT and KO_b/c at baseline (timepoint 0), but after 1 day of MAc the pH of KO_b/c mice was significantly less than WT mice (timepoint 1). (D) For assessing % change from baseline, pH was converted to [H⁺]. When normalized to baseline, both WT and KO_b/c mice exhibited a significant % change in [H⁺] in response to MAc (WT: p = 0.039, KO_b/c: p < 0.001; RM-ANOVA), however the % change in [H⁺] after 1 day of MAc was significantly greater in KO_b/c mice than WT mice (timepoint 1). (E) [HCO₃ ⁻]. There were no significant differences between WT and KO_b/c [HCO₃ ⁻] at baseline or during the MAc challenge. (F) When normalized to baseline, both WT and KO_b/c mice exhibited a significant % change in [HCO₃ ⁻] in response to MAc (WT: p < 0.001, KO_b/c: p < 0.001; RM-ANOVA), but there were no significant differences in the % change in [HCO₃ ⁻] on any day of the MAc-challenge. *p < 0.05 between WT and KO_b/c mice at each day noted, assessed by Student’s 2-tailed unpaired t-test; ns, non-significant; WT: n = 7M/6F; KO_b/c: n = 6M/8F.