NDT Advance Access originally published online on March 29, 2007
Nephrology Dialysis Transplantation 2007 22(7):1856-1863; doi:10.1093/ndt/gfm138
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Treatment of hyponatraemia by urea decreases risks of brain complications in rats. Brain osmolyte contents analysis
1Department of Internal Medicine, Jolimont/Tubize-Nivelles Hospital, 2Research Unit for the Study of Hydromineral Metabolism, Free University of Brussels, Brussels, Belgium, 3Department of Medicine, Rochester General Hospital, University of Rochester School of Medicine, NY, USA and 4Department of General Internal Medicine, Erasmus University Hospital, Free University of Brussels, Brussels, Belgium
Correspondence and offprint requests to: Alain Soupart, MD, PhD, Research Unit for the Study of Hydromineral Metabolism, Department of General Internal Medicine, Free University of Brussels, Hôpital Erasme, 808, Route de Lennik, 1070 Brussels, Belgium. Email: alainsoupart{at}swing.be
 |
Abstract |
|---|
Background. Brain damage (myelinolysis) develops in hyponatraemia after a large increase in serum sodium regardless of the currently available methods of correction. However, a preliminary study suggests that treatment of hyponatraemia with urea limits the risks of brain lesions in rats. Benefits of sustained high blood levels of urea and mechanisms of protection remain hypothetical.
Methods. In the first part of the study, hyponatraemic rats received repeated (i.p.) doses of urea (2 g/kg b.w./6 h) leading to sustained blood levels (urea ± 230 mg/dl). Neurologic outcome was compared to correction of hyponatraemia by water diuresis. In the second part of the study, we analysed the adaptative response of the brain to correction of hyponatraemia with either urea or water diuresis, by measurement of cerebral osmolyte contents.
Results. Despite a large correction of the serum sodium (mean 
SNa = 32 mEq/l/24 h), mortality rate (13%) and neurological symptoms were low in the urea-treated group contrary to control groups treated by water diuresis (mortality: 87%). This shows with stronger evidence the protective effect of urea against brain myelinolysis. In the second part, analysis of brain composition shows that, in the urea groups, 24 h after correction, intracerebral hyperionization (NaCl) was avoided and brain water contents remained normal. No significant changes of the major brain organic osmolyte composition were observed after urea administration except reaccumulation of betaine. No difference in brain composition was noted regarding concomitant plasma urea levels (> or <150 mg/dl).
In rats treated by water diuresis, the brain remained also significantly depleted in organic osmolytes 24 h after correction, but contrary to administration of urea, this treatment was associated with a high mortality rate.
Conclusions. These comparative results suggest a specific brain-protective effect of urea itself against myelinolysis.
Keywords: brain; hyponatraemia; osmotic demyelinating syndrome; urea
Received for publication: 27. 7.06
Accepted in revised form: 21. 2.07
CiteULike 
Connotea 
Del.icio.us What's this?
Related articles in NDT:
- In this issue ...
NDT 2007 22: i.[Extract] [FREE Full Text]
This article has been cited by other articles:
|
|
 |
|
  R. Zietse, N. van der Lubbe, and E. J. Hoorn Current and future treatment options in SIADH NDT Plus, November 1, 2009; 2(suppl_3): iii12 - iii19. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. P. Costanzo and R. E. Lee Jr Urea loading enhances freezing survival and postfreeze recovery in a terrestrially hibernating frog J. Exp. Biol., September 15, 2008; 211(18): 2969 - 2975. [Abstract] [Full Text] [PDF]
|
|