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Published on: September 18, 2014
Altered contractile responsiveness in ileal longitudinal muscle after total gastrectomy in a rat model
Sehsuvar Gokgoz1, Gokhan Koyluoglu, Serpil Saraydin
1Department of Surgery, Cumhuriyet University School of Medicine, 58140 Sivas, Turkey.
Purpose:
To test the hypothesis that the changes in ileal smooth muscle contractility accompanying postgastrectomy syndromes are agonist-specific, we investigated the effects of potassium chloride (KCl), carbachol, substance P (SP), and serotonin on ileal smooth muscle contractility after total gastrectomy in rats.
Methods:
We performed total gastrectomy in ten rats and a sham operation in another ten rats as a control. All of the rats were killed and their ileums excised 4 weeks postoperatively. The concentration-response relationships for KCl, SP, and serotonin were obtained by adding each agent cumulatively to the organ bath. Morphological changes in the ileum were also examined by light microscopy.
Results:
There was no significant difference between the responsiveness of gastrectomized and control tissues to KCl. Maximum responses (E(max)) to carbachol and SP were less in the gastrectomized ileal segments than in the control ileal segments. E(max) to serotonin was higher in the gastrectomized ileal segments than in the control ileal segments. The pD(2)value, i.e., the negative logarithm of the concentration for the half-maximal response, EC(50), for carbachol, SP, and serotonin was unchanged in the gastroctomized ileal segments and the control segments. Total gastrectomy also caused morphological changes in the ileum.
Conclusions:
These data indicate that the contractile response to various agents is altered after total gastrectomy and that receptor-mediated mechanisms may cause these changes.
Insights
Total gastrectomy alters rat ileal smooth muscle contractility in an agonist-specific manner, affecting responses to carbachol, substance P, and serotonin, but not potassium chloride.
Area of Science:
- Gastroenterology
- Pharmacology
- Physiology
Background:
- Postgastrectomy syndromes can involve altered gastrointestinal motility.
- Understanding changes in ileal smooth muscle contractility is crucial for managing these syndromes.
Purpose of the Study:
- To investigate agonist-specific effects on ileal smooth muscle contractility after total gastrectomy in rats.
- To test if changes in contractility are dependent on the specific stimulating agent (potassium chloride, carbachol, substance P, serotonin).
Main Methods:
- Total gastrectomy was performed on rats, with a sham operation serving as the control group.
- Ileal segments were excised 4 weeks postoperatively for contractility studies.
- Concentration-response relationships for potassium chloride, substance P, and serotonin were determined using cumulative addition in organ baths; carbachol effects were also assessed. Morphological changes were examined.
Main Results:
- Ileal smooth muscle responsiveness to potassium chloride remained unchanged post-gastrectomy.
- Maximum contractile responses (Emax) to carbachol and substance P were significantly reduced in gastrectomized rats.
- Emax to serotonin was increased, while the potency (pD2) for carbachol, substance P, and serotonin was unaltered. Morphological changes were observed.
Conclusions:
- Total gastrectomy significantly alters ileal smooth muscle contractile responses in an agonist-specific manner.
- These alterations suggest that receptor-mediated mechanisms are involved in the changes observed after gastrectomy.
