Fig. 5

Aging- and FBS-dependent regulatory mechanisms of body fluid pH via transporting systems of Cl⁻ and HCO₃⁻. A Age effects on venous serum Cl⁻ concentration ([Cl⁻]_s). a Younger persons with normal mitochondrial function. Glucose is metabolized into pyruvic acid, and then CO₂ is produced from the pyruvic acid in mitochondria with normal function. The produced CO₂ moves into erythrocytes, and is converted into H⁺ and HCO₃⁻ via a CA-facilitated process. The HCO₃⁻ is exchanged with serum Cl⁻ via a Cl⁻/HCO₃ anion exchanger (AE). These processes lead to low [Cl⁻]_s. b Older persons with low mitochondrial function. The amount of CO₂ produced in mitochondria becomes low due to low mitochondrial function. Thus, the amount of H⁺ and HCO₃⁻ produced from CO₂ becomes low. These processes keep high [Cl⁻]_s. B FBS/HbA1c effects on [Cl⁻]_s. with normal mitochondrial function. Glucose is metabolized into pyruvic acid, and then CO₂ is produced from the pyruvic acid in mitochondria with normal function. The produced CO₂ moves into erythrocytes, and is converted into H⁺ and HCO₃⁻ via a CA-facilitated process. The HCO₃⁻ is exchanged with serum Cl⁻ via a Cl⁻/HCO₃ anion exchanger (AE). In cases of high FBS/HBA1c with normal mitochondrial function, large amounts of CO₂ are produced, resulting in production of large amounts of HCO₃⁻. These processes lead to low [Cl⁻]_s. Figure 5 has been originally published in Marunaka et. al. (2021) Int J Mol Sci 22:11111 [237] under a Creative Commons Attribution-NonCommercial 4.0 International License