At @ hours , the mean serum potassium level had decreased from @ mmol per liter at baseline to @ mmol per liter in the group of patients who received @ g of ZS-@ , @ mmol per liter in the @-g group , and @ mmol per liter in the @-g group , for mean reductions of @ , @ , and @ mmol per liter , respectively ( P < @ for all comparisons ) and to @ mmol per liter in the @-g group and the placebo group ( mean reduction , @ mmol per liter ) .