Anion effects on cation movements during correction of potassium depletion.

The differential effects of KCl vs. KHCO3 for intravenous K+ repletion were evaluated in a series of nephrectomized dogs previously depleted of 20% of total-body K by a 2-wk regimen consisting of K-free diet plus DOCA plus chlorothiazide. Twenty-four percent of K losses (5% of original TBK) were replaced by a 2-h infusion of either CKl or KHCO3. Blood pH was maintained at normal levels by controlling the rate of respiration. Skeletal muscle biopsies were taken before and 2 h after repletion, and blood samples were taken at intervals throughout. The following differences resulting from KHCO3 compared to KCl repletion were found: a) a greater cellular K uptake, a lower rate of increase, and a lower steady-state extracellular K+ concentration; b) a less increase in intracellular K+ concentration and a less decrease in intracellular Na+ concentration. These differences, which were independent of extracellular pH or kidney function, are thought to be secondary to unequal distribution of Cl- and HCO3-ions.