Changes in respiratory sensations induced by lobeline after human bilateral lung transplantation

Abstract

The sensations evoked by the injection of lobeline into the right antecubital vein were studied in 8 subjects after bilateral lung transplantation and 10 control subjects. In control subjects, two distinct sensations were experienced. There was an early noxious sensation (onset ≈10 s) followed by a late sensation of breathlessness (onset ≈26 s) associated with involuntary hyperventilation. The early sensation was accompanied by respiratory and cardiovascular changes. In contrast to control subjects, the early respiratory events and the noxious sensations evoked by injections of lobeline (18‐60 μg kg−1) did not occur in subjects with recent bilateral lung transplantation. This suggests that the early respiratory sensations are mediated by the discharge of receptors in the lungs. The late hyperventilation and the accompanying sensation of breathlessness occurred in both transplant and control subjects and are therefore likely to be mediated by receptors elsewhere in the body, presumably systemic arterial chemoreceptors stimulated by lobeline. In control subjects, but not transplant subjects, there was a consistent decrease in mean arterial pressure associated with the lobeline injection. This suggests that pulmonary afferents mediate the hypotension. For transplant subjects studied more than a year after transplantation, there was some evidence that the noxious respiratory sensations evoked by lobeline had returned. This suggests that some functional reinnervation of pulmonary afferents may occur.

Effects of Preconditioning on the Resistance to Acute Hypobaric Hypoxia and Their Correction with Selective Antagonists of Nicotinic Receptors

“…NCR of the α 7 subtype are an essential component in the mechanism of adaptation in low resistant rats. An in vitro (neocortex) and in vivo study (myocardium) showed that activation of α 7 NCR is analogues (1); highly resistant animals (2). Light bars, LS 1 after primary testing (random division of rats to low resistant and highly resistant specimens, n=11/10); dark bars, LS 2 after repeated testing in control groups (n=6/4); shaded bars, LS 2 in groups of HBH (n=5/6).…”

An Official American Thoracic Society Statement: Update on the Mechanisms, Assessment, and Management of Dyspnea

“…Some evidence suggests that relief of air hunger from lung and chest expansion is attenuated in lung transplant patients compared with heart transplant patients and healthy subjects, suggesting a greater role for pulmonary stretch receptors than chest wall receptors (103,111). However, these studies were performed before it was discovered that transplanted lungs are re-innervated quickly, and thus may have overestimated the contribution of chest wall receptors (112).…”

Cough and ventilatory adjustments evoked by aerosolised capsaicin and distilled water (fog) in man

“…It is well documented that humans are able to sense and evaluate respiratory changes such as those induced by respiratory loads, bronchoconstriction, lung volume, airway pressure, changes in ventilation and blood gas tensions (see Davenport et al, 2002), and by i.v. administrations of chemicals (Raji et al, 1995;Butler et al, 2001). However, little is known on sensations evoked by inhalation of tussigenic agents.…”