Vagal afferents reflexly inhibit exercise in conscious rats.

Title

Vagal afferents reflexly inhibit exercise in conscious rats.

Creator

DiCarlo S E; Collins H L; Chen C Y

Publisher

Medicine and science in sports and exercise

Date

1994
1994-04

Description

Activation of vagal afferents reflexly inhibited locomotion induced by stimulation of the mesencephalic locomotor region in decerebrate cats. However, this reflex has not been tested in intact mammals. Therefore, the purpose of this study was to test the hypothesis that vagal afferent stimulation would inhibit somatomotor activity in the intact conscious rat. Six Sprague-Dawley rats were chronically instrumented with carotid arterial and femoral venous catheters and electromyogram (EMG) electrodes inserted into the biceps femoris muscle. Cardiac autonomic efferent blockade [atropine methyl bromide (14 mg.kg-1, i.v.) and metoprolol (14 mg.kg-1, i.v.)] and alpha-adrenergic receptor blockade [phenoxybenzamine (5 mg.kg-1, i.v.)] was achieved to prevent bradycardia and hypotension. Vagal afferents were stimulated (phenyl-biguanide 2.5 and 5.0 micrograms.kg-1 i.v.) during steady state exercise (9.0 m.min-1, 10% grade). Phenyl-biguanide decreased exercise EMG activity 30 +/- 6% and 54 +/- 10% in a dose dependent manner without significantly altering mean arterial pressure or heart rate. We speculate that this reflex may serve as a negative feedback mechanism to indirectly reduce myocardial oxygen demands during exercise.

Subject

Animals; Rats; Action Potentials/drug effects/physiology; Electromyography; Blood Pressure/drug effects/physiology; Physical Exertion/*physiology; Consciousness; Heart Rate/drug effects/physiology; Afferent Pathways/drug effects/physiology; Biguanides/administration & dosage/*pharmacology; Motor Activity/*drug effects/*physiology; Muscles/drug effects/physiology; Reflex/*drug effects/*physiology; Serotonin Receptor Agonists/administration & dosage/*pharmacology; Vagus Nerve/*drug effects/*physiology; Dose-Response Relationship; Drug; Sprague-Dawley

Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

459–462

Issue

4

Volume

26

Citation

DiCarlo S E; Collins H L; Chen C Y, “Vagal afferents reflexly inhibit exercise in conscious rats.,” NEOMED Bibliography Database, accessed October 28, 2021, https://neomed.omeka.net/items/show/4912.

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