Alteration of the responses of gastric smooth muscle to endothelin in streptozotocin-induced diabetic rats
| Autor: | Kenro Imaeda, Naotsuka Okayama, Yoshinobu Kamiya, Kazuko Wakami, Ryosuke Kimura, Takashi Kato, T. Mizuno, Takashi Joh, Kazuhiro Yamada, Fumie Ryuge |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Blood Glucose
Agonist medicine.medical_specialty Physiology medicine.drug_class Stomach Diseases Motility Isometric exercise Diabetes Mellitus Experimental Diabetes Complications Rats Sprague-Dawley Diabetes mellitus Internal medicine Pyloric Antrum medicine Animals Receptor Antrum Endothelin-1 Chemistry Body Weight Stomach Muscle Smooth General Medicine medicine.disease Streptozotocin Receptor Endothelin B Rats Endocrinology Endothelin receptor Muscle Contraction medicine.drug |
| Zdroj: | Journal of Smooth Muscle Research. 43:191-199 |
| ISSN: | 1884-8796 0916-8737 |
| DOI: | 10.1540/jsmr.43.191 |
| Popis: | Diabetic gastropathy is suggested to be the result of not only an autonomic neuropathy but also to disorder of the spontaneous rhythmic motility of the gastric smooth muscle. Attempts were made to investigate the alteration of the effects of endothelin-1 (ET-1), which is known to enhance the spontaneous activity of gastrointestinal smooth muscle, on gastric activity in streptozotocin (STZ)-induced diabetic rats. STZ-induced diabetic rats were prepared by the injection of Sprague-Dawley (SD) rats with STZ (i.p.). Isometric mechanical responses were recorded in isolated circular smooth muscle strips of the stomach antrum, to measure changes in the rhythmicity of the smooth muscle. ET-1 (10 nM) significantly elevated the resting tension and the frequency of spontaneous contraction, but did not alter the amplitude of the spontaneous oscillatory contractions in normal rats. In diabetic rats, ET-1 elevated the resting tension, and spontaneous contractions were increased in frequency, however they were decreased in amplitude. In normal rats, sarafotoxin S6c (S6c, 10 nM), a selective ET(B) receptor agonist, elevated the resting tension slightly and increased both the frequency and amplitude of the spontaneous contractions. However, S6c significantly elevated the resting tension alone in STZ-induced diabetic rats. Selective stimulation of endothelin type A (ET(A)) receptors with ET-1, in the presence of a selective antagonist of ET(B) receptors, produced similar responses in the gastric muscle of both normal and diabetic rats. These results indicate that ET-1 elevates the resting tension and increases the frequency of the spontaneous oscillatory contractions in both normal and STZ-induced diabetic rats, to a similar extent. However, the specific actions on ET(B) receptors were quite different between the two: the elevating actions on the resting tension were much greater in STZ-diabetic rats than in normal rats. The results suggested the facilitation of ET(B) receptor signaling in the antrum during the pathogenesis of diabetic gastropathy. |
| Databáze: | OpenAIRE |
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