title: Effect of water deprivation, desmopressin (DDAVP) infusion, and oral loads of water, Na+ and NH4+ on urinary excretion of epidermal growth factor in the rat.
abstract: Epidermal growth factor (EGF) is synthesized in the kidneys and excreted in urine. Administration of exogenous EGF modulates the reabsorption of Na+ and the vasopressin stimulated reabsorption of water in the collecting tubules. In order to clarify whether this reflects a physiological role for urinary EGF we examined the effects of changes in the oral loads of water, Na+ and NH4+ as well as the effect of infusion of the vasopressin analogue, desmopressin (DDAVP) on the endogenous urinary EGF excretion in the rat. Water deprivation for 48 h reduced the urinary excretion of EGF by 25% and the urinary EGF/creatinine ratio by 8%. Also, urinary volume, Na+ excretion, and urinary pH were reduced by water deprivation. Infusion of DDAVP, low plasma vasopressin induced by polydipsia, and changes in the renal excretion of Na+ and H+ did not affect the urinary excretion of EGF.
  
  
  CONCLUSIONS
  it seems unlikely that nephrogenous EGF excreted in the urine plays a physiological role in the regulation of the renal excretion of Na+ and H+ and in the vasopressin stimulated reabsorption of water in the rat. However, since water deprivation reduced the urinary excretion of EGF it remains possible that urinary EGF plays a role in the complex physiological response to dehydration.
authors: Department of Clinical Chemistry, KH University Hospital of Aarhus, Denmark.
authors: P E
authors: PE
authors: Jørgensen
authors: S S
authors: SS
authors: Poulsen
authors: E
authors: E
authors: Nexø
authors: S
authors: S
authors: Christensen
mesh_terms: D000284:Administration, Oral; D000643:Ammonium Chloride / Q000494:pharmacology*; D000818:Animals; D003894:Deamino Arginine Vasopressin / Q000494:pharmacology*; D004815:Epidermal Growth Factor / Q000187:drug effects* / Q000652:urine*; D005260:Female; D007260:Infusion Pumps; D007279:Injections, Subcutaneous; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000494:pharmacology* / Q000652:urine; D014867:Water / Q000494:pharmacology*; D014868:Water Deprivation / Q000502:physiology*
chemical_list: D000643:Ammonium Chloride; D014867:Water; D004815:Epidermal Growth Factor; D012964:Sodium; D003894:Deamino Arginine Vasopressin