Alterations in spontaneous contractions of rat ileum and jejunum after peritonitis

Comparison of In Vitro Effects of Opioid Analgesics on Spontaneous Proximal and Distal Colon Contractions in Healthy Rats and Rats with Peritonitis

Objective

The goal of this study was to investigate and compare the effects of opioids on proximal and distal colon contractions in normal rats and rats with peritonitis, with and without the presence of naloxone in the environment.

Methods

The study was approved by Cumhuriyet University Ethics committee. In this study, 16 Wistar Albino male rats were used. Rats were divided into two groups. Peritonitis was induced using a cecum ligation and perforation method, 24 h before the tissues of rats in the peritonitis group were collected, and sham surgery was performed 24 h before the tissues of rats in the control group were collected. Twenty-four hours after the surgery, rats' organs were harvested and hung in organ baths. Concentration-dependent inhibitory effects of morphine and meperidine on spontaneous intestinal movements were observed. Any differences between the groups were tested using the Kruskal-Wallis test, and any differences between the groups were tested using the Tukey test.

Results

No significant difference was observed between the proximal and distal colon smooth muscle contraction responses in both groups after 80 mM Potassium Chloride (KCl) injection (p>0.005). In the peritonitis group, amplitudes and frequencies of spontaneous contractions in proximal and distal colon significantly increased (p<0.05). Drugs decreased the amplitude and frequency responses in the control group (p<0.05). In the peritonitis group, whereas morphine decreased the amplitude and frequency responses in comparison with the control group (p<0.05), meperidine did not cause any significant changes (p>0.05). In both groups, adding naloxone to the organ baths before adding opioids completely blocked the morphine's inhibitory effect on the amplitude and frequency (p<0.05), but it could not completely block the inhibition caused by meperidine.

Conclusion

Morphine and meperidine exhibit an inhibitory effect on the intestinal motility in both groups. This effect can be blocked by naloxone completely in morphine, and partially in meperidine.

Effects of proton pump inhibitors and h(2) receptor antagonists on the ileum motility

Objectives. To investigate the effects of proton pump inhibitors (PPIs) and H₂ receptor antagonists on ileum motility in rats with peritonitis and compare changes with control group rats. Methods. Peritonitis was induced by cecal ligation and puncture in 8 rats. Another of 8 rats underwent a sham operation and were accepted as controls. Twenty-four hours later after the operation, the rats were killed, and their ileum smooth muscle was excised and placed in circular muscle direction in a 10 mL organ bath. Changes in amplitude and frequency of contractions were analyzed before and after PPIs and H₂ receptor blockers. Results. PPI agents decreased the motility in a dose-dependent manner in ileum in both control and intraabdominal sepsis groups. While famotidine had no significant effect on ileum motility, ranitidine and nizatidine enhanced motility in ileum in both control and intraabdominal sepsis groups. This excitatory effect of H₂ receptor antagonists and inhibitor effects of PPIs were significantly high in control group when compared to the peritonitis group. The inhibitor effect of pantoprazole on ileum motility was significantly higher than the other two PPI agents. Conclusions. It was concluded that H₂ receptor antagonists may be more effective than PPIs for recovering the bowel motility in the intraabdominal sepsis situation.

Altered spontaneous contractions of the ileum by anesthetic agents in rats exposed to peritonitis

AIM: To investigate in vitro effects of propofol, midazolam and dexmedetomidine, which are commonly used anaesthesic or sedatives, on spontaneous contractions of the ileum both in normal rats and those exposed to hyperdynamic peritonitis.

METHODS: Spontaneous contractions of isolated ileum muscle segments from sham operated rats and those exposed to peritonitis, were studied in vitro. The amplitude and the frequency of spontaneous contractions of ileum muscle segments were studied after adding dexmetetomidine, propofol, and midazolam to the organ bath in a cumulative manner.

RESULTS: Both amplitude (85.2 ± 6.6 vs 47.4 ± 7.1) and frequency (32.8 ± 4.6 vs 20.2 ± 3.9) of spontaneous contractions in ileum smooth muscle segments were decreased significantly in the peritonitis group compared to the control group (P < 0.05). Dexmedetomidine significantly increased the amplitude of spontaneous contractions (85.2 ± 6.6 vs 152.0 ± 5.4, P < 0.05) whereas, propofol (85.2 ± 6.6 vs 49.6 ± 4.8, P < 0.05) and midazolam (85.2 ± 6.6 vs 39.2 ± 4.5, P < 0.05) decreased it in both control and peritonitis groups. The frequency of spontaneous contractions were significantly decreased by propofol in both control (32.8 ± 4.6 vs 18.2 ± 3.4, P < 0.05) and peritonitis groups 20.2 ± 3.9 vs 11.6 ± 3.2, P < 0.05). Dexmedetomidine and midazolam did not cause significant changes in the number of spontaneous contractions in both control and the peritonitis groups (P > 0.05).

CONCLUSION: Propofol, midazolam and dexmede-tomidine have various in vitro effects on spontaneous contractions of the rat ileum. While dexmedetomidine augments the spontaneous contraction of the rat ileum, propofol attenuates it. However, the effects of these compounds were parallel in both control and peritonitis groups.