Validation of a novel technique allowing assessment of the functional role of cardiac prejunctional receptors in the rat
| Autor: | Chantal Thiry, Icilio Cavero |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Atropine
Male Sympathetic nervous system Neuromuscular Junction Stimulation Blood Pressure Thymus Gland Betaxolol Clonidine chemistry.chemical_compound Heart Rate Mecamylamine medicine Animals Pharmacology business.industry General Neuroscience Heart Rats Inbred Strains Receptors Adrenergic alpha Spinal cord Electric Stimulation Ganglion Rats Receptors Adrenergic medicine.anatomical_structure chemistry Spinal Cord Hexamethonium business Neuroscience Idazoxan medicine.drug |
| Zdroj: | Journal of autonomic pharmacology. 10(2) |
| ISSN: | 0144-1795 |
| Popis: | 1. The electrical stimulation of the thoracic portion of the spinal cord (preganglionic nerve fibres) in the pithed rat is a widely used technique to investigate drug effects on the sympathetic nervous system. However, it does not allow discrimination between ganglionic and neuronal ending sites of action of drugs. This report describes and validates an experimental approach in which postganglionic nerve fibres are stimulated in pithed rats, thereby overcoming the above mentioned difficulty. 2. Electrical stimulation of a nerve below the thymus gland produced frequency-related increases in heart rate which were not modified by the ganglion blockers, hexamethonium or mecamylamine, but were reduced by the beta 1-adrenoceptor antagonist, betaxolol. Thus, the studied nerve fibres can be classified as sympathetic postganglionic neurons. 3. The parameters for electrical stimulation of postganglionic cardioaccelerator nerve fibres giving optimal responses were of similar pulse widths as required for the stimulation of the thoracic spinal cord, but of lower strength of current, higher frequencies and shorter stimulation times to achieve steady-state responses. 4. Clonidine reduced the tachycardia evoked by sustained electrical stimulation of postganglionic cardioaccelerator nerve fibres. This effect was antagonized entirely by the selective alpha 2-adrenoceptor antagonist, idazoxan. Therefore, sympathetic cardiac postganglionic nerve fibres are endowed with alpha 2-adrenoceptors. |
| Databáze: | OpenAIRE |
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