Table 2.

Acid-base and electrolyte status of acid-loaded proton receptor knockout mice (GPR4−/−) and their wild types (GPR4+/+)

GenotypeGPR4+/+GPR4−/−P
Blood
    n1010
    pH7.35 ± 0.027.32 ± 0.020.3
    PCO233 ± 1.734 ± 2.40.7
    PO296.5 ± 296.2 ± 4.60.9
    HCO318.3 ± 0.817.8 ± 0.50.6
    tCO219.3 ± 0.818.8 ± 0.50.7
    K+5.3 ± 0.065.4 ± 0.10.4
    Na+148.5 ± 1.7150 ± 1.10.4
    Cl123 ± 4.5133 ± 3.30.3
    iCa+1.05 ± 0.061.1 ± 0.050.3
    BEecf−7.3 ± 1−7 ± 0.40.7
    creatininea0.018 ± 0.00070.018 ± 0.00020.6
    BUNa27 ± 3.329 ± 20.5
Urine
    n55
    pH5.85 ± 0.036.0 ± 0.070.2
    osmolarity4065 ± 1522991 ± 4420.051
    creatinine4.9 ± 0.15 ± 0.40.8
    K+/creatinine65.5 ± 2.765.6 ± 1.30.9
    Na+/creatinine31.4 ± 0.830.5 ± 1.60.6
    Cl/creatinine120.6 ± 3.5117.6 ± 6.30.7
    Ca2+/creatinine0.2 ± 0.010.3 ± 0.03b0.02
    NH4+/creatinine62.6 ± 244.9 ± 4.4c0.006
    TA/creatinine19.8 ± 2.521 ± 0.90.6
    NAE/creatinine82.3 ± 3.466 ± 5.1b0.03
    NAE0.93 ± 0.030.66 ± 0.03d0.0007
    creatinine clearance0.4 ± 0.020.4 ± 0.020.5
  • Blood samples were obtained from the tail artery in conscious mice.

  • aWe used five wild types and five knockout animals for the measurements of blood creatinine and BUN. Urine analyses were performed on samples collected in metabolic cages during a 24-hour period. (Urine pH and ammonium measurements were also repeated in fresh urine samples to avoid artifacts associated with the prolonged collection of urine in metabolic cages.) Concentrations of electrolytes, anion gap, creatinine, and titratable acids (TA) were expressed in mmol/L, NAE was expressed in mmol/24 hours, ratios of urine electrolytes versus creatinine were expressed as mmol/L versus mmol/L, and BUN was expressed in mg/dl, creatinine clearance in ml/min, osmolarity in mOsmol/L, and PCO2 in mmHg. Acid-base and urine electrolyte parameters of wild-type mice at baseline were significantly different from the parameters measured in the acid-loaded wild types. Similarly, acid-base and electrolyte parameters of GPR4−/− mice at baseline were significantly different from the parameters of acid-loaded GPR4−/− mice (Supplement 5).

  • bP < 0.05.

  • cP < 0.01.

  • dP < 0.005.