The time course and magnitude of the effect of single slow and rapid respiratory manoeuvres on specific airway conductance (sGaw) was assessed in seven normal control subjects and in seven heart-lung transplant (HLT) recipients before and after experimentally induced bronchoconstriction. 2. Neither full inspiration, full exhalation nor vital capacity manoeuvres significantly altered sGaw in normal controls or HLT recipients under baseline conditions despite the presence of hyper-responsiveness to methacholine (MC) in the latter group. 3. After induced bronchoconstriction, single slow and rapid inspirations to total lung capacity transiently abolished or attenuated the bronchoconstriction in normal controls. This effect was absent in the HLT recipients. 4. In HLT recipients, the combination of hyper-responsiveness to MC, the absence of bronchoconstriction with respiratory manoeuvres and the absence of significant bronchodilatation after deep inspiration suggest lack of normal pulmonary innervation.
