title: Synergistic effects of hypertonic saline and valproic acid in a lethal rat two-hit model.
abstract: BACKGROUND
  Hemorrhagic shock (HS) followed by an infection ("second hit") can lead to severe systemic inflammatory response and multiple-organ failure. Studies have shown that resuscitation with hypertonic saline (HTS) can blunt the inflammatory response. We demonstrated that large doses of valproic acid (VPA, 300 mg/kg), a histone deacetylase inhibitor, improves survival in a rodent two-hit model (HS followed by cecal ligation and puncture [CLP]). In the present study, we examined whether combination of HTS with VPA would allow us to achieve survival advantage at a lower dose of VPA (200 mg/kg).
  
  
  METHODS
  Male Sprague-Dawley rats were subjected to HS (50% blood loss) and randomized into five groups (n = 7-8 per group) as follows: (1) isotonic sodium chloride solution (ISCS), (2) 7.5% saline, (3) VPA, (4) ISCS + VPA, and (5) HTS + VPA. After 24 hours, they underwent CLP, followed by the same doses of ISCS, HTS, and/or VPA and were monitored for 10 days. In a parallel experiment, blood, peritoneal irrigation fluid and lung homogenate were subjected to enzyme-linked immunosorbent assay 3 hours and 24 hours after CLP to measure myeloperoxidase activity and proinflammatory cytokines tumor necrosis factor α and interleukin 1β levels. Western blotting was performed to investigate the expression of pentraxin 3 protein in the lung homogenate at 24 hours after CLP. Hematoxylin and eosin staining of lungs at the 24 hours were performed to quantify the degree of acute lung injury.
  
  
  RESULTS
  HTS + VPA treatment significantly improved survival (87.5%), compared with the other groups (14.3%; p < 0.05), while attenuating peritoneal myeloperoxidase levels and proinflammatory cytokine tumor necrosis factor α and interleukin 1β levels in the serum, peritoneal cavity, and lung. The degree of acute lung injury and expression of pentraxin 3 in the lung were significantly reduced in the HTS + VPA group.
  
  
  CONCLUSIONS
  This is the first study to show that VPA and HTS can work synergistically to attenuate inflammation and improve survival in a lethal two-hit model.
authors.affiliation: Division of Trauma, Emergency Surgery and Surgical Critical Care, Department of Surgery, Massachusetts General Hospital/Harvard Medical School, Boston, MA, USA.
authors.forename: Zhengcai
authors.initials: Z
authors.lastname: Liu
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Li
authors.forename: Baoling
authors.initials: B
authors.lastname: Liu
authors.forename: Danielle K
authors.initials: DK
authors.lastname: Deperalta
authors.forename: Ting
authors.initials: T
authors.lastname: Zhao
authors.forename: Wei
authors.initials: W
authors.lastname: Chong
authors.forename: Xiuzhen
authors.initials: X
authors.lastname: Duan
authors.forename: Peter
authors.initials: P
authors.lastname: Zhou
authors.forename: George C
authors.initials: GC
authors.lastname: Velmahos
authors.forename: Hasan B
authors.initials: HB
authors.lastname: Alam
mesh_terms: D055371:Acute Lung Injury / Q000188:drug therapy* / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002097:C-Reactive Protein / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D004797:Enzyme-Linked Immunosorbent Assay; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012151:Resuscitation / Q000379:methods*; D012462:Saline Solution, Hypertonic / Q000627:therapeutic use*; D000683:Serum Amyloid P-Component / Q000378:metabolism; D014635:Valproic Acid / Q000627:therapeutic use*; D000099153:Pentraxins
chemical_list: D002097:C-Reactive Protein; D016207:Cytokines; D004791:Enzyme Inhibitors; D012462:Saline Solution, Hypertonic; D000683:Serum Amyloid P-Component; D014635:Valproic Acid; D000099153:Pentraxins