Table 3.

Metabolic measurementsa

Low KNormal KHigh K
Initial body weight (g)29.7 ± 0.728.8 ± 0.529.8 ± 0.6
Final body weight (g)25.6 ± 0.526.9 ± 0.327.3 ± 0.6
Plasma K+ (mM)b4.13 ± 0.224.08 ± 0.224.85 ± 0.2
Plasma Na+ (mM)c145.4 ± 0.4146 ± 0.6144.3 ± 0.7
Plasma Cl (mM)d114.4 ± 1.54112 ± 1114.5 ± 1.05
Plasma creatinine (μM)e13.8 ± 2.2414.4 ± 1.2112.5 ± 1.44
Aldosterone (nM)0.834 ± 0.2970.793 ± 0.2071.879 ± 0.387
Renin activity (ng/ml per h)4.38 ± 1.124.45 ± 0.835.71 ± 0.34
Corticosterone (nmol/L)345.8 ± 48.8342 ± 58.2300 ± 42.6
  • a Plasma concentrations of Na+, K+, Cl, and creatinine were measured on commercial clinical chemistry analyzers and remained within the normal range for all groups. Plasma renin activity (PRA), aldosterone, corticosterone, and plasma electrolyte measurements were performed in samples that were removed on cardiac puncture during terminal anaesthetic. Blood samples were centrifuged, and plasma was removed, put on ice, and rapidly stored at −20°C. Aliquots of plasma for assay of PRA were thawed, and buffer stabilizing renin activity was added immediately. PRA (40) and corticosterone (41) were assayed as previously described (40,41). PRA and corticosterone did not change significantly. Aldosterone levels were measured using a radioimmunoassay kit (Coat-a-Count aldosterone; DPC, Los Angeles, CA). Values are means ± SEM.

    Normal plasma ranges for

  • b K+, 3.0 to 8.3 mmol/L (35), but carefully taken having a narrower range probably nearer 3.8 to 6.8 mmol/L (3638);

  • c Na+, 139 to 157 mmol/L;

  • d Cl, 104 to 119 mmol/L (39);

  • e creatinine, 5 to 67 μmol/L (35).