Hexamethonium-induced augmentation of the electrical twitch response in the guinea-pig ileum longitudinal muscle-myenteric plexus strip
| Autor: | Josef Donnerer, Ingrid Liebmann, Ulrike Holzer-Petsche |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Male
medicine.medical_specialty Guinea Pigs Myenteric Plexus Nicotinic Antagonists Biology Hexamethonium Tonic (physiology) chemistry.chemical_compound Ileum Internal medicine medicine Purinergic P2 Receptor Antagonists Animals PPADS Guanethidine Myenteric plexus General Neuroscience Purinergic receptor Muscle Smooth musculoskeletal system Electric Stimulation Endocrinology Nicotinic agonist chemistry Pyridoxal Phosphate Cholinergic medicine.drug Muscle Contraction |
| Zdroj: | Neuroscience letters. 577 |
| ISSN: | 1872-7972 |
| Popis: | Longitudinal muscle-myenteric plexus strips of the guinea-pig ileum were used to investigate the nature of the hexamethonium-induced augmentation of the twitch response. All preparations were set up in Tyrode solution and intermittent longitudinal twitch contractions were evoked by single pulse electrical field stimulation. Hexamethonium, a blocker of nicotinic ganglionic transmission, at 300 μmol/l and 1 mmol/l augmented the twitch contractions by 21% and 35%, respectively. First we tested for a possible nicotinic drive onto an inhibitory neuronal component to the longitudinal smooth muscle cells. However, guanethidine (5 μmol/l), naloxone (1 μmol/l), or l-NAME (300 μmol/l) were without effect on the hexamethonium-induced augmentation. The P2 purinoceptor antagonist pyridoxalphosphate-6-azophenyl-2'-4'-disulphonic acid (PPADS), 25-100 μmol/l, without altering the control twitch responses, dose-dependently reduced the hexamethonium-induced augmentation; at 100 μmol/l a statistically significantly inhibition was observed. Based on these functional experiments we found no evidence that blocking nicotinic transmission removed a tonic adrenergic, opioidergic or nitrergic inhibitory input to the longitudinal muscle. However, we provide evidence for a hexamethonium-induced augmentation of the P2 purinergic input to cholinergic motoneurons of the guinea-pig ileum longitudinal muscle. The P2-nicotinic receptor interaction presents a novel modulatory mechanism to cholinergic myenteric motor neurons. |
| Databáze: | OpenAIRE |
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