title: Comparison of equivolume, equiosmolar solutions of mannitol and hypertonic saline with or without furosemide on brain water content in normal rats.
abstract: BACKGROUND
  Mannitol and hypertonic saline (HS) are used by clinicians to reduce brain water and intracranial pressure and have been evaluated in a variety of experimental and clinical protocols. Administering equivolume, equiosmolar solutions in healthy animals could help produce fundamental data on water translocation in uninjured tissue. Furthermore, the role of furosemide as an adjunct to osmotherapy remains unclear.
  
  
  METHODS
  Two hundred twenty isoflurane-anesthetized rats were assigned randomly to receive equivolume normal saline, 4.2% HS (1,368 mOsm/L 25% mannitol (1,375 mOsm/L), normal saline plus furosemide (8 mg/kg), or 4.2% HS plus furosemide (8 mg/kg) over 45 min. Rats were killed at 1, 2, 3, and 5 h after completion of the primary infusion. Outcome measurements included body weight; urinary output; serum and urinary osmolarity and electrolytes; and brain, lung, skeletal muscle, and small bowel water content.
  
  
  RESULTS
  In the mannitol group, the mean water content of brain tissue during the experiment was 78.0% (99.3% CI, 77.9-78.2%), compared to results from the normal saline (79.3% [99.3% CI, 79.1-79.5%]) and HS (78.8% [99.3% CI, 78.6-78.9%]) groups (P < 0.001), whereas HS plus furosemide yielded 78.0% (99.3% CI, 77.8-78.2%) (P = 0.917). After reaching a nadir at 1 h, brain water content increased at similar rates for mannitol (0.27%/h [99.3% CI, 0.14-0.40%/h]) and HS (0.27%/h [99.3% CI, 0.17-0.37%/h]) groups (P = 0.968).
  
  
  CONCLUSIONS
  When compared to equivolume, equiosmolar administration of HS, mannitol reduced brain water content to a greater extent over the entire course of the 5-h experiment. When furosemide was added to HS, the brain-dehydrating effect could not be distinguished from that of mannitol.
authors: Department of Surgery, College of Medicine, National Cheng Kung University, Tainan, Taiwan, Republic of China.
authors: Liang Chao
authors: LC
authors: Wang
authors: Alexander
authors: A
authors: Papangelou
authors: Christopher
authors: C
authors: Lin
authors: Marek A
authors: MA
authors: Mirski
authors: Allan
authors: A
authors: Gottschalk
authors: Thomas J K
authors: TJ
authors: Toung
mesh_terms: D000818:Animals; D001834:Body Water / Q000187:drug effects*; D001921:Brain / Q000187:drug effects*; D004232:Diuretics / Q000494:pharmacology; D004234:Diuretics, Osmotic / Q000494:pharmacology*; D005665:Furosemide / Q000494:pharmacology*; D007427:Intracranial Pressure / Q000187:drug effects; D008297:Male; D008353:Mannitol / Q000494:pharmacology*; D009994:Osmolar Concentration; D051381:Rats; D017208:Rats, Wistar; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*
chemical_list: D004232:Diuretics; D004234:Diuretics, Osmotic; D012462:Saline Solution, Hypertonic; D008353:Mannitol; D005665:Furosemide