Role of the autonomic nervous system in the development of cardiovascular changes during nasal apnoea and lung inflation
Javorka, K.; Tomori, Z.
Physiologia Bohemoslovaca 25(6): 511-518
1976
ISSN/ISBN: 0369-9463 PMID: 139626 Document Number: 106175
The role of the sympathetic system in the development of bradycardia during nasal apnea and the role of the sympathetic and parasympathetic system in the development of cardiovascular changes during and immediately after lung inflation were determined in anesthetized rabbits. Transection of the cervical cord (C5-7) completely blocked the hypertensive response to chemical stimulation of the nasal mucosa. The degree of nasal bradycardia was 72% lower than in stimulation of the controls. Propranolol had no effect on the hypertensive reaction, but inhibited nasal bradycardia, which was 68% lower than in the controls. Lung inflation induced tachycardia, which was only non-significantly reduced by bilateral vagotomy. Vagotomy inhibited the bradycardiac response to removal of occlusion of the trachea and the subsequent rise in blood pressure. Cervical cord transection did not reduce inflation-induced tachycardia, but it significantly influenced the heart rate during the 2nd phase of prolonged inflation, when the heart is affected by hypoxia. Inflation-induced tachycardia was not influenced by bilateral vagotomy associated with cervical cord transection. Similar cardiac responses also occur in the presence of the simple increase in pericardial pressure produced by left pneumothorax without lung inflation.