Responses of slowly and rapidly adapting receptors in the airways of rabbits to changes in the Starling forces.

Abstract

SUMMARY1. The responses of the rapidly adapting receptors (RARs) and the slowly adapting receptors (SARs) of the airways to changes in the Starling forces regulating fluid exchange in the pulmonary extravascular space were investigated in anaesthetized rabbits. The hydrostatic pressure in the pulmonary microvasculature was raised by partial obstruction of the mitral valve (mean left atrial pressure increased by approximately 5 and 10 mmHg above the control values) and the concentration of plasma proteins was reduced by plasmapheresis (the total plasma protein concentration reduced by 18 %).2. There was a significant correlation between the action potentials generated by RARs and mean left atrial pressure (n = 12). A similar response was not observed in SARs (n = 12).3. After plasmapheresis, there was an increase in the resting activity of the RARs (n = 5). In addition, the stimulus-response curve relating mean left atrial pressure and RAR activity was significantly shifted to the left compared to the one elicited before plasmapheresis. Plasmapheresis failed to influence the activity of SARs (n = 5).4. Obstruction of the pulmonary lymph flow by raising the afterload in the right external jugular vein caused a significant increase in the activity of RARs (n = 6). This response was also maintained during the entire period of lymphatic obstruction.5. The results show that manipulation of the Starling forces within the lung influences the RAR activity profoundly. It is suggested that the stimulus for the RARs may be a function of the fluid fluxes in the pulmonary extravascular space.

Serial changes in nasal potential difference and lung electrical impedance tomography at high altitude

“…However, if subclinical pulmonary edema is of hydrostatic origin, it is likely to occur at much lower Ppas than those seen in clinical HAPE. Hargreaves et al (13) demonstrated increased activity in rabbit airway rapidly adapting receptors suggestive of a physiological effect from interstitial edema after an increase in left atrial pressure of as little as 5 mmHg. In keeping with the findings of Boussuges et al (3), we also found alterations in transmitral flow on echo-Doppler with a decrease in the E/A ratio on ascent to high altitude, suggestive of a reduction in left ventricular diastolic compliance.…”

Risk Factors for Coughing in Dogs with Naturally Acquired Myxomatous Mitral Valve Disease

“…According to these observations, pulmonary edema should not be an expected cause of cough, unless fluid accumulation is severe enough to build up within the airways, producing a soft moist cough accompanied by blood‐tinged sputum . Although there is a reported correlation between action potentials generated by coughing receptors and mean left atrial pressure in anesthetized rabbits, a direct association between resulting peribronchial edema and coughing is not reported . Nevertheless, in many veterinary textbooks, cough commonly is associated with the presence of cardiogenic pulmonary edema in dogs .…”

Airway irritation and cough evoked by acid: from human to ion channel

“…Stimulation of C-fibers in the airways is known to trigger the release of substance P and other tachykinins [19], which can in turn lead to the production of nitric oxide from endothelial cells [34]; nitric oxide, an endogenous free radical gas, can increase the microvascular permeability and fluid infiltration into the perivascular interstitial space in the airways, and activate RARs [35]. Indeed, it has been shown that right atrial injection of lactic acid stimulates a small percentage of RARs in the rat lung [36].…”