Lf. Menegon et al., Effect of chronic metabolic acidosis on renal growth and renal sodium handling in uninephrectomized rats, RENAL FAIL, 21(1), 1999, pp. 13-22
Paucity studies have indicated that a systemic metabolic acidosis cause a d
ecrease in salt and wafer reabsorption in the kidney. The following study w
as undertaken on male Wistar-Hannover rats (200-250 g) to investigate the e
ffects of a chronic, NH4Cl-induced metabolic acidosis on the renal handling
of Na+ in sham-operated and uninephrectomized rats by lithium clearance. T
he present study shows that chronic acidosis (blood pH, 7.16 +/- 0.13) caus
ed a sustained increase in renal fractional Na+ excretion (267.9 +/- 36.4%)
, accompanied by a rise in the fractional proximal (113.3 +/- 3.6%) and pos
t-proximal (179. 7 +/- 20.2%) Na+ and fractional K+ (163.4 +/- 5.6%) excret
ions when compared to pair-fed rats. These differences occurred in spite of
an unchanged creatinine clearance and Na+ filtered load. On the other hand
, a body growth impairment was observed in the acidotic (control, 258 +/- 3
. 7 g versus acidotic, 232 +/- 4.6 g) and pair-fed rats (225 +/- 3.6 g), wh
ereas there Mm significant enhance in the kidney weights in acidotic rats (
1.73 +/- 0.05 g) compared to other experimental groups (control, 1.46 +/- 0
.05 g; pair-fed 1.4 +/- 0.05 g). The renal growth indexes after metabolic a
cidosis NH4Cl-induced did not shown statistical difference at 1.5, 3.0 and
12 hours after uninephrectomy when were compared with pair-fed groups. Howe
ver, from the fifth to tenth day after unilateral nephrectomy the renal gro
wth index of acicdotic group was significantly greater than pair-Sed groups
. Unilateral nephrectomy in acidotic animals caused a striking additional b
ut transient increase in fractional renal sodium (FENa+) and potassium (FEK
+) excretion from 1.5 to 3 hours post-surgery meanly associated with an enh
anced post-proximal sodium excretion when compared to pair-fed uninephrecto
mize rats. By the fifth postoperative day the all functional values returne
d to baseline levels. This altered renal Na+ handling and K+ excretion may
result from a reciprocal relationship between tubular metabolic pathway sti
muli and ion transport Further studies are required to investigate the acid
osis involvement an functional kidney response.