GABAA and GABAB receptor-mediated effects on the spontaneous activity of the longitudinal layer in cat terminal ileum
| Autor: | K. Venkova, Nevena Pencheva, R. Radomirov |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
Male
Baclofen medicine.medical_specialty Sesterterpenes Tetrodotoxin In Vitro Techniques GABAB receptor Bicuculline Inhibitory postsynaptic potential GABA Antagonists chemistry.chemical_compound Ileum Internal medicine medicine Animals Picrotoxin gamma-Aminobutyric Acid Pharmacology Muscimol GABAA receptor musculoskeletal neural and ocular physiology Receptors GABA-A GABA-A receptors GABA-B receptors cat erminal ileum spontaneous activity Endocrinology nervous system chemistry Cats GABAergic Gastrointestinal Motility Muscle Contraction medicine.drug |
| Zdroj: | General Pharmacology: The Vascular System. 22:159-163 |
| ISSN: | 0306-3623 |
| Popis: | 1. 1. GABA and GABAergic agonists—muscimol and (±)baclofen changed the spontaneous mechanical activity in isolated cat terminal ileum. 2. 2. GABA at doses ranging from 5 μM to 2 mM produced concentration-dependent biphasic responses consisting of a transient relaxation followed by contractions with a tonic and a phasic components. 3. 3. The GABA-induced relaxation was sensitive to bicuculline and picrotoxinin and was mimicked by muscimol, while the GABA-induced contractions were insensitive to bicuculline and picrotoxinin and were mimicked by (±)baclofen. Specific cross desensitization occurred between GABA and muscimol or GABA and (±)baclofen. 4. 4. The bicuculline-sensitive relaxation induced by GABA and muscimol was abolished by atropine or tetrodotoxin (TTX), while the bicuculline-insensitive contractions induced by GABA and (±)baclofen were not antagonized by atropine or TTX, though they were slightly suppressed. 5. 5. The GABA effects in the longitudinal layer of cat terminal ileum were mediated by the following receptors: −GABA A prejunctional receptors whose activation causes relaxation, probably through an inhibitory action on cholinergic neurons; −GABA B prejunctional receptors whose activation cause contractions; −GABA B postjunctional receptors located on the smooth muscle membrane whose activation induces tonic and phasic contractions. |
| Databáze: | OpenAIRE |
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