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Carbon monoxide involved in modulating HCO3- secretion in rat duodenum.
Hironori Takasuka1, Shusaku Hayashi, Masafumi Koyama
1Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Kyoto, Japan.
Carbon monoxide (CO) stimulates duodenal bicarbonate secretion via prostaglandins. Endogenous CO, produced by heme oxygenase (HO), also plays a protective role in maintaining duodenal mucosal integrity.
Area of Science:
- Gastroenterology
- Physiology
- Biochemistry
Background:
- The duodenum secretes bicarbonate (HCO3-) to neutralize gastric acid.
- Carbon monoxide (CO) is an emerging signaling molecule with diverse physiological roles.
- Heme oxygenase (HO) enzymes produce endogenous CO.
Purpose of the Study:
- To investigate the effect of exogenous CO donor (CORM-2) on rat duodenal HCO3- secretion.
- To determine the role of endogenous CO (via HO) in regulating duodenal HCO3- secretion.
- To explore the involvement of prostaglandins (PGs) and mucosal integrity.
Main Methods:
- Rat duodenal loops were perfused under anesthesia.
- HCO3- secretion was measured using a pH stat method.
- Effects of CORM-2, HO inhibitors (SnPP), PG synthesis inhibitors (indomethacin), and acid challenge were assessed.
Main Results:
- CORM-2 dose-dependently increased duodenal HCO3- secretion, mediated by prostaglandins.
- Acid-induced HCO3- secretion and mucosal damage were exacerbated by HO inhibition (SnPP) and indomethacin.
- HO-1 protein expression was upregulated following acid treatment.
Conclusions:
- Exogenous and endogenous CO stimulate duodenal HCO3- secretion through prostaglandin pathways.
- The heme oxygenase/carbon monoxide (HO/CO) system is crucial for maintaining duodenal mucosal integrity.
- CO plays a significant role in duodenal physiology and protection.
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