Urinary concentrating mechanism and Aquaporin-2 abundance in rats chronically treated with aluminum lactate.

Abstract

The aim of this work was to study the effects of chronic administration of aluminum (Al) on the urinary concentrating and diluting mechanisms in the distal tubules and collecting ducts. Male Wistar rats were chronically treated with aluminum lactate for 12 weeks (0.575 mg Al/100g of body weight, i.p., three times per week). After 12 weeks, renal function of control and Al-treated rats was evaluated by clearance techniques. To study urinary concentrating mechanisms, renal function was also measured in control and Al-treated rats deprived of water, after the administration of desmopressin (vasopressin agonist) and after the infusion of hypertonic saline at increasing infusion rates. Sodium and water balance were impaired. We found decreased urinary concentrating ability in situations in which endogenous (thirst or infusion of hypertonic saline) or exogenous plasma antidiuretic hormone was increased. Solute-free water formation, measured during the infusion of hypotonic saline showed normal transport in the thick ascending limb. Aquaporin-2 (AQP2) expression was measured by Western blot to evaluate water permeability in collecting ducts. We found that Al produced downregulation of AQP2 in plasma membranes and intracellular vesicles, that could account for the impaired water handling. Administration of desmopressin increased AQP2 in plasma membranes, suggesting that Al did not impair trafficking of this protein, but could interfere with AQP2 synthesis.

• Authors: Stella Mahieu, Néstor Millen, María del Carmen Contini, Marcela Gonzalez, Sara M Molinas, María Mónica Elías
• Journal: Toxicology (Toxicology) Vol. 223 Issue 3 Pg. 209-18 (Jun 15 2006) ISSN: 0300-483X [Print] Ireland
• PMID: 16675087 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Aluminum Compounds
• Aquaporin 2
• Lactates
• Saline Solution, Hypertonic
• Deamino Arginine Vasopressin
• aluminum lactate

Topics

• Aluminum Compounds (toxicity)
• Animals
• Aquaporin 2 (metabolism)
• Deamino Arginine Vasopressin (pharmacology)
• Drinking Behavior
• Kidney Concentrating Ability (drug effects)
• Kidney Tubules (drug effects, metabolism, physiopathology)
• Lactates (toxicity)
• Male
• Protein Transport
• Rats
• Rats, Wistar
• Saline Solution, Hypertonic
• Time Factors
• Urinalysis