Effects of single breath lung inflation on the pattern of subsequent breaths

In rabbits, on release of lung inflations 0.4 to 3.3 times control V t and lasting 1 to 30 sec, V t, peak diaphragmatic activity (Ep) and inspiratory duration (Ti) increased, whereas expiratory duration (Te) decreased relative to pre-inflation values. Similar changes occurred between pre- and postinflation occluded breaths. These changes lasted from a few breaths up to 30 sec, and were positively correlated with magnitude and duration of inflations. Postinflation changes of pulmonary stretch receptor activity were relatively small and limited to 1–3 breaths. At chemical drive close to control: (a) postinflation V t (itvs) Ti relationship moved to the right without changing its slope, Ti occluded eventually exceeding Ti after vagotomy; (b) the Te vs Ti relationship moved downwards, its slope being decreased and eventually abolished; (c) the average rate of rise of E was decreased. An increase of V t, Ep and Ti, and a decrease Te also occurred on release of stimulation of the central ends of the cut vagi producing apnea at FRC in mono- and bilateral vagotomized rabbits. Postinflation effects were mainly of central origin and tentatively explained as rebound phenomena within the respiratory center.