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Hydrogen peroxide reduces beta-adrenoceptor function in the rat small intestine
1Department of Pharmacochemistry, Faculty of Chemistry, Vrije Universiteit, Amsterdam, The Netherlands.
European Journal of Pharmacology
|June 25, 1991
Summary
Hydrogen peroxide (H2O2) impairs rat intestinal beta-adrenoceptor function by disrupting receptor-mediated cyclic AMP production. This suggests H2O2 alters membrane integrity, affecting smooth muscle relaxation.
Area of Science:
- Pharmacology
- Gastroenterology
- Cellular Biology
Background:
- Beta-adrenoceptors regulate intestinal smooth muscle relaxation.
- Hydrogen peroxide (H2O2) is an oxidative stress agent that can affect cellular function.
Purpose of the Study:
- To investigate the effect of H2O2 on beta-adrenoceptor-mediated relaxation in isolated rat intestinal segments.
- To determine the cellular mechanism underlying H2O2-induced impairment of beta-adrenoceptor signaling.
Main Methods:
- Isolated rat intestinal segments were incubated with varying concentrations of H2O2.
- Relaxation responses to isoprenaline, a beta-adrenoceptor agonist, were measured.
- Responses to dibutyryl-cAMP and forskolin were assessed to probe downstream signaling.
Main Results:
- H2O2 significantly decreased the maximal relaxation induced by isoprenaline in a dose-dependent manner.
- The impairment was more pronounced in the ileum compared to the duodenum.
- Responses to dibutyryl-cAMP and forskolin were less affected, suggesting the issue lies upstream of adenylate cyclase.
Conclusions:
- H2O2 disrupts beta-adrenoceptor coupling in rat intestinal smooth muscle.
- The findings suggest altered receptor-mediated cyclic AMP production, likely due to compromised membrane integrity.
- This oxidative stress impacts the ability of the intestine to relax in response to beta-adrenergic stimulation.