Most sodium reabsorbed in the proximal tuble is coupled to
A)secretion of Ca^ 2+
B)secretion of K^ +
C)secretion of Cl^-
D)reaabsorption of K^ +
E) reabsorption of HCO 3 ^ -
A)secretion of Ca^ 2+
B)secretion of K^ +
C)secretion of Cl^-
D)reaabsorption of K^ +
E) reabsorption of HCO 3 ^ -