title: Effect of metabolic acidosis on renal tubular sodium handling in rats as determined by lithium clearance.
abstract: Systemic metabolic acidosis is known to cause a decrease in salt and water reabsorption by the kidney. We have used renal lithium clearance to investigate the effect of chronic, NH4Cl-induced metabolic acidosis on the renal handling of Na+ in male Wistar-Hannover rats (200-250 g). Chronic acidosis (pH 7.16 +/- 0.13) caused a sustained increase in renal fractional Na+ excretion (267.9 +/- 36.4%), accompanied by an increase in fractional proximal (113.3 +/- 3.6%) and post-proximal (179.7 +/- 20.2%) Na+ and urinary K+ (163.4 +/- 5.6%) excretion when compared to control and pair-fed rats. These differences occurred in spite of an unchanged creatinine clearance and Na+ filtered load. A lower final body weight was observed in the acidotic (232 +/- 4.6 g) and pair-fed (225 +/- 3.6 g) rats compared to the controls (258 +/- 3.7 g). In contrast, there was a significant increase in the kidney weights of acidotic rats (1.73 +/- 0.05 g) compared to the other experimental groups (control, 1.46 +/- 0.05 g; pair-fed, 1.4 +/- 0.05 g). We suggest that altered renal Na+ and K+ handling in acidotic rats may result from a reciprocal relationship between the level of metabolism in renal tubules and ion transport.
authors.affiliation: Disciplina de Medicina Interna, Laboratório de Balanço Hidro-Salino, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, SP, Brasil.
authors.forename: L F
authors.initials: LF
authors.lastname: Menegon
authors.forename: J F
authors.initials: JF
authors.lastname: Figueiredo
authors.forename: J A
authors.initials: JA
authors.lastname: Gontijo
mesh_terms: D000141:Acidosis, Renal Tubular / Q000378:metabolism*; D000818:Animals; D001835:Body Weight; D007668:Kidney / Q000033:anatomy & histology; D008094:Lithium / Q000378:metabolism*; D008297:Male; D009929:Organ Size; D011188:Potassium / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism*
chemical_list: D008094:Lithium; D012964:Sodium; D011188:Potassium