Abstract:
Background. The mechanisms involved in the impaired
gallbladder contractile response in peritonitis
are unknown. The aim of this study was to determine
the effect of peritonitis on the contraction and relaxation
responses to different agonists in gallbladder
smooth muscle in guinea pig.
Materials and methods. Peritonitis was induced by
cecal ligation and puncture (CLP) in 10 guinea pigs.
Another group of 10 guinea pigs underwent a sham
operation and acted as controls. Twenty-four hours
after the operation, the guinea pigs were killed, and
gallbladder strips were placed in organ bath. The contraction
responses to KCl, carbachol, and histamine,
and relaxation responses to cyclooxygenase inhibitors
(indomethacin, nimesulide, and DFU) on KCl-induced
contractions were recorded.
Results. There was no significant difference between
the contractile responsiveness to KCl, but maximum
contractile responses (Emax) to carbachol and histamine
were significantly reduced. Indomethacin, nimesulide,
and DFU concentration dependently inhibited
on KCl-induced contractions of gallbladder smooth
muscle. Emax values of indomethacin, nimesulide, and
DFU were significantly reduced in the peritonitis
group compared with controls (P < 0.05). The inhibitor
effects of nimesulide and DFU were considerably similar,
but inhibitor effect of indomethacin was signifi-
cantly less than that measured for nimesulide and
DFU in both control and peritonitis groups (P < 0.05).
Conclusions. The contraction responses to carbachol
and histamine and relaxation responses to COX inhibitors
on gallbladder smooth muscle are significantly
decreased by peritonitis. Although the mechanism ofthe decrease in contraction and relaxation responses
in CLP-induced peritonitis is completely unknown, we
speculate that impaired smooth muscle responses may
be related to an alteration in the regulation of
receptor/postreceptor excitation-response coupling
and/or through changes on Ca2 influx.
