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On the phasic reflex bronchodilation in the cat
J García Ramos1, A Hernández Alcaráz, C Eguía
1Laboratorio de Neurofisiología, Facultad de Medicina, Universidad Autónoma de Querétaro, México.
Acta Physiologica, Pharmacologica Et Therapeutica Latinoamericana : Organo De La Asociacion Latinoamericana De Ciencias Fisiologicas Y [De] La Asociacion Latinoamericana De Farmacologia
|January 1, 1994
Summary
Vagal nerve stimulation in cats causes bronchodilation, influencing breathing patterns. These bronchomotor responses can track changes in the central respiratory generator
Area of Science:
- * Neurophysiology
- * Respiratory Physiology
- * Autonomic Nervous System
Background:
- * Tracheal pressure and flow recordings in anesthetized cats reveal significant pressure-negative excursions.
- * These responses to vagal nerve stimulation were previously attributed solely to inspiratory muscle contractions.
Purpose of the Study:
- * To investigate the role of phasic bronchodilation in response to vagal nerve stimulation.
- * To explore the modulation of these bronchomotor responses under various physiological and experimental conditions.
Main Methods:
- * Electrophysiological recordings of tracheal pressure and flow in anesthetized cats.
- * Vagal nerve stimulation using single pulses and constant current (d.c.).
- * Assessment of responses following lung sympathectomy, hiccups, and exaggerated sympathetic activity.
Main Results:
- * Vagal nerve stimulation elicits significant pressure-negative, air inflow excursions attributed to phasic bronchodilation.
- * Bronchodilation occurs during inspiration and can be facilitated during expiration, post-hyperventilatory apnea, or d.c. vagal stimulation.
- * Responses are reduced by lung sympathectomy and exhibit long-term depression (LTD) after hiccups or long-term potentiation (LTP) after repetitive/d.c. vagal stimulation, and are potentiated with increased sympathetic activity.
Conclusions:
- * Phasic bronchodilation is a significant component of the response to vagal nerve stimulation.
- * Bronchomotor responses are modulated by sympathetic activity and exhibit plasticity (LTD/LTP).
- * These responses serve as a reliable indicator of excitability changes in the central respiratory generator.