Responses of C fiber afferents of the rabbit airways and lungs to changes in extra-vascular fluid volume

• Published in: Respiratory physiology & neurobiology 2002-09, Vol.132 (3), p.239-251
• Main Authors: Gunawardena, S, Ravi, K, Longhurst, J.C, Kaufman, M.P, Ma, Amy, Bravo, Milo, Kappagoda, C.T
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Afferent Pathways - physiology; Airway Obstruction - physiopathology; Animals; Biological and medical sciences; Electrophysiology; Lymph flow, pulmonary, obstruction, lung receptors; Lymphatic System - physiopathology; Male; Mammals, rabbit; Medical sciences; Mitral Valve Insufficiency - physiopathology; Nerve Fibers, Unmyelinated - physiology; Plasmapheresis - methods; Pneumology; Pulmonary Artery - physiology; Pulmonary Artery - physiopathology; Pulmonary Edema - physiopathology; Pulmonary Stretch Receptors - physiopathology; Rabbits; Receptors, bronchial, pulmonary, extravascular fluid volume; Respiratory system : syndromes and miscellaneous diseases; Venous Cutdown; Venous Pressure
• ISSN: 1569-9048; 1878-1519
• DOI: 10.1016/S1569-9048(02)00114-3

Effects of changes in extra-vascular fluid volume produced by pulmonary lymphatic obstruction and plasmapheresis on the activities of bronchial and pulmonary C fiber receptors and rapidly adapting receptors (RARs) were investigated in New Zealand White rabbits. In intact rabbits, pulmonary lymphatic obstruction either alone or in combination with plasmapheresis did not stimulate pulmonary C fiber receptors. Only the combined stimulus activated the bronchial C fiber receptors. Bronchial C fiber receptors were also stimulated by graded increases in left atrial pressure (+5 and +10 mmHg). In contrast, RARs were activated by lymphatic obstruction either alone or in combination with plasmapheresis. These procedures increase the extra-vascular fluid volume in the carina and bronchi but not in the lungs (alveoli). In rabbits with chronic pulmonary venous congestion secondary to mitral valve damage, bronchial C fiber receptors were not stimulated by these increments in left atrial pressure which were insufficient to increase the extra vascular fluid content of the airways. However, both pulmonary and bronchial C fiber receptors were stimulated when the left atrial pressure was raised to 25 mmHg in these animals to cause pulmonary edema.