Figure 3. ENaC activation and sodium retention in nephrotic nphs2^Δipod*plg^+/+ and nphs2^Δipod*plg^−/− mice.

(A)Natriuretic response to vehicle (injectable water, 5 μl g⁻¹ bw) or amiloride (10 μg g⁻¹ bw i.p.). in uninduced and nephrotic nphs2^Δipod*plg^+/+ and nphs2^Δipod*plg^−/− mice. Urine was collected for 6 h after injection and all mice underwent vehicle and amiloride injection sequentially (at day −21 and day 8, respectively). Mean values were 34 ± 7 and 26 ± 9 μmol 6 h⁻¹ in uninduced nphs2^Δipod*plg^+/+ (n=10) and nphs2^Δipod*plg^−/− mice (n=11) receiving vehicle and 93 ± 11 and 91 ± 11 μmol 6 h⁻¹ receiving amiloride injection. In nephrotic nphs2^Δipod*plg^+/+ (n=9) and nphs2^Δipod*plg^−/− mice (n=8) vehicle injection was followed by a significantly reduced urinary sodium excretion (3 ± 1 and 5 ± 1 μmol 6 h⁻¹, respectively). After amiloride injection urinary sodium excretion increased to 110 ± 26 and 159 ± 27 μmol 6 h⁻¹, respectively.

(B) Amiloride-sensitive natriuresis as the fold increase. In uninduced nphs2^Δipod*plg^+/+ and nphs2^Δipod*plg^−/− mice this ratio was 4 ± 1 (n=10) and 9 ± 3 (n=11), respectively, in nephrotic nphs2^Δipod*plg^+/+ and nphs2^Δipod*plg^−/− mice 72 ± 26 and 63 ± 16, respectively.

(C, D) Course of urinary sodium excretion in spot urine samples and body weight taken in the morning after induction of nephrotic syndrome in nphs2^Δipod*plg^+/+, nphs2^Δipod*plg^−/− mice and control mice, respectively.

Arithmetic means ± SEM, ^# indicates significant difference to baseline value, * indicates significant difference between genotypes, § indicates significant difference between uninduced and nephrotic state. A: amiloride; U: uninduced; N: nephrotic. V: vehicle.