Postnatal changes in vagal control of esophageal muscle contractions in rats
| Autor: | Yasutake Shimizu, Chiaki Nakamori, Takahiko Shiina |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
Atropine
medicine.medical_specialty Ganglionic Blockers Tubocurarine Stimulation Muscarinic Antagonists Nicotinic Antagonists Mecamylamine Receptors Nicotinic Biology Hexamethonium General Biochemistry Genetics and Molecular Biology chemistry.chemical_compound Esophagus Pregnancy Internal medicine medicine Animals Rats Wistar General Pharmacology Toxicology and Pharmaceutics Muscle Skeletal Acetylcholine receptor Heart Vagus Nerve General Medicine Anatomy Acetylcholine Electric Stimulation Rats Vagus nerve Protein Subunits medicine.anatomical_structure Endocrinology Animals Newborn chemistry Female Muscle Contraction medicine.drug |
| Zdroj: | Life Sciences. 90:495-501 |
| ISSN: | 0024-3205 |
| Popis: | Aims Replacement of smooth muscles by striated muscles occurs in the esophagus during the early postnatal period. The aim of this study was to clarify postnatal changes in vagal control of esophageal muscle contractions in rats. Main methods An isolated segment of the neonatal rat esophagus was placed in an organ bath and the contractile responses were recorded using a force transducer. Key findings Electrical stimulation of the vagus trunk evoked a biphasic contractile response in the neonatal esophageal segment. The first and second components of the contractions were inhibited by α-bungarotoxin and atropine, respectively. Ganglion blockers, hexamethonium and mecamylamine, did not affect vagally mediated contractions. The first component gradually enlarged with age in days, whereas the second component declined during the first week after birth. Application of d -tubocurarine or acetylcholine caused an apparent contraction in the esophageal striated muscle at postnatal day 0, but responses to these drugs were not observed at 1 week after birth. The neonatal esophagus expressed the γ-subunit of nicotinic acetylcholine receptors. In contrast, the e-subunit was dominantly expressed in the adult esophagus. Significance The vagus nerves directly innervate both the esophageal striated muscles and smooth muscles in the early neonatal period. During the process of muscle rearrangement, the property of the striated muscles is altered substantially. The specific features of striated muscles in the neonatal rat esophagus might compensate for immature formation of neuromuscular junctions. Unsuccessful conversion of the striated muscle property during postnatal muscle rearrangement would be related to disorders of esophageal motility. |
| Databáze: | OpenAIRE |
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