Limits of brain tolerance to daily increments in serum sodium in chronically hyponatraemic rats treated with hypertonic saline or urea: advantages of urea.
1. At present there is no consensus about the optimal management of hyponatraemia to prevent demyelinating brain lesions. We have evaluated in a large series of rats (n = 136) the protective role of urea for the brain in the treatment of severe chronic hyponatraemia. Urea (group I, n = 51) was compared with hypertonic saline in boluses (group II, n = 46) and with hypertonic saline in divided doses (group III, n = 39). Treatment was administered intraperitoneally over 48 h. The severity of brain lesions was assessed by histological scoring. 2. For 95% of the injured animals treated with hypertonic saline, brain lesions appeared for an absolute increment in serum Na+ concentration (delta SNa+) of 20 mmol day-1 l-1. Above this limit neurological injuries gradually worsened, and beyond a transition zone (delta SNa+ greater than or equal to 20 less than or equal to 23 mmol day-1 l-1) 89% (group III) to 100% (group II) of the animals were injured. This limit can be reached rapidly, as attested by the comparable severity of brain lesions observed in group II (mean delta SNa+ 1 h after a bolus injection, 19 mmol/l) and in group III (mean delta SNa+ 1 h after an injection, 2 mmol/l), both groups achieving similar daily delta SNa+. 3. A correction above the threshold of 20 mmol day-1 l-1 is as toxic during the first 24 h as during the second day of the treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Soupart
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A
Department of Internal Medicine, Erasmus University Hospital, Brussels, Belgium.
Stenuit
A
A
Perier
O
O
Decaux
G
G
D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D002908:Chronic Disease; D003711:Demyelinating Diseases / Q000473:pathology / Q000517:prevention & control*; D007010:Hyponatremia / Q000188:drug therapy*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012462:Saline Solution, Hypertonic / Q000627:therapeutic use; D012964:Sodium / Q000097:blood*; D014508:Urea / Q000627:therapeutic use*
D012462:Saline Solution, Hypertonic; D014508:Urea; D012964:Sodium