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Abstract: The aim of this study was to investigate the effects of peritonitis on spontaneous contractions of ileum and jejunum smooth muscles isolated from rats. Peritonitis was induced by cecal ligation and puncture in 8 rats. Another group of 8 rats underwent a sham operation and acted as controls. Twenty-four hours after the operation, the rats were killed, and their ileum and jejunum smooth muscles were excised and placed in circular muscle direction in a 10 ml organ bath. Changes in the amplitude and frequency of spontaneous contractions were analyzed before and after the addition of different antagonists. Peritonitis induced the decrease in the amplitude and frequency of spontaneous contractions in ileum and jejunum smooth muscles. In control groups, both ileum and jejunum, the amplitude and frequency of spontaneous contractions were significantly elevated in the presence of N G-nitro-l-arginine (l-NNA) and indomethacin. In peritonitis groups, both ileum and jejunum, the amplitude and frequency of spontaneous contractions were significantly enhanced in the presence of l-NNA, aminoguanidine, indomethacin and celecoxib compared to control values. In conclusion, peritonitis induces the decrease in the amplitude and frequency of spontaneous contractions of ileum and jejunum that can be attributed to the rise of nitric oxide synthase and cyclooxygenase isoforms levels. [Copyright &y& Elsevier]

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 significantly 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 of the 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. [Copyright &y& Elsevier]