Transient receptor potential vanilloid 1 antagonist, capsazepine, improves survival in a rat hemorrhagic shock model.
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.
Akabori
Hiroya
H
Department of Surgery, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga, Japan 520-2192.
Yamamoto
Hiroshi
H
Tsuchihashi
Hiroshi
H
Mori
Tsuyoshi
T
Fujino
Kazunori
K
Shimizu
Tomoharu
T
Endo
Yoshihiro
Y
Tani
Tohru
T
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
D002395:Catecholamines; C071423:capsazepine; D002211:Capsaicin