title: Transient receptor potential vanilloid 1 antagonist, capsazepine, improves survival in a rat hemorrhagic shock model.
abstract: OBJECTIVE
  To evaluate the role of transient receptor potential vanilloid 1 (TRPV1) in a rat hemorrhagic shock (HS) model using the TRPV1 antagonist, capsazepine (CPZ).
  
  
  BACKGROUND
  TRPV1, distributed within the sensory nerve, plays a role in the regulation of cardiovascular functions. TRPV1 may be involved in the cardiovascular responses to HS.
  
  
  METHODS
  Male rats were anesthetized and HS was induced with the mean arterial pressure (MAP) at 30 mm Hg for 90 minutes. CPZ (5.0 micromol/kg) was administered at 30 minutes after the shock induction, and the 24-hour survival rates were assessed. The MAP, heart rate, and shed blood volume (SBV) were recorded throughout the experiment. Arterial blood gas analysis and the plasma catecholamines levels were measured before and after HS. Double-immunohistochemistry for Fos and tyrosine hydroxylase (TH) was performed in the rostral ventrolateral medulla (RVLM) of the brain.
  
  
  RESULTS
  CPZ significantly improved the 24-hour survival rates, which was accompanied by the increase in the MAP and the SBV, a decrease of the plasma catecholamines levels, and attenuation of the severe metabolic acidosis. Furthermore, CPZ reduced the percentage of double-labeled neurons for Fos and TH in the RVLM of the rat brain.
  
  
  CONCLUSIONS
  TRPV1 may be involved in the regulation of the cardiovascular responses to HS, at least in part, by recruiting catecholaminergic neurons in the RVLM. CPZ appears to induce metabolic compensations, which may be potentially useful in HS.
authors.affiliation: Department of Surgery, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga, Japan 520-2192.
authors.forename: Hiroya
authors.initials: H
authors.lastname: Akabori
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsuchihashi
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Mori
authors.forename: Kazunori
authors.initials: K
authors.lastname: Fujino
authors.forename: Tomoharu
authors.initials: T
authors.lastname: Shimizu
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Endo
authors.forename: Tohru
authors.initials: T
authors.lastname: Tani
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002211:Capsaicin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002395:Catecholamines / Q000097:blood; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D007124:Immunoenzyme Techniques; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012771:Shock, Hemorrhagic / Q000188:drug therapy*; D015996:Survival Rate
chemical_list: D002395:Catecholamines; C071423:capsazepine; D002211:Capsaicin