Neutrophil influx into guinea-pig airway lumen during cholinergic and non-cholinergic bronchoconstriction

Sensory nerve activation will produce adherence of neutrophils to tracheobronchial microvessels. The aim of the present study was to investigate whether this adherence would lead to an influx of neutrophils into the airway lumen. To do this, we studied the effects of 20 minutes of vagal stimulation (1 Hz, 5 ms, 5 V) in anaesthetized and tracheostomized guinea-pigs on both lung resistance, and the cell picture in bronchoalveolar lavage. Any changes were compared to those of intravenous methacholine infusion, producing similar changes in lung resistance. Since high pressure ventilation could produce lung damage, we also studied the effects of ventilation through an extracorporeal resistor, producing a similar change in transpulmonary pressure (45 +/- 2 cmH2O) as vagal stimulation (42 +/- 4 cmH2O). The total number of cells recovered in the lavage was not increased by vagal stimulation, methacholine infusion or the extracorporeal resistor. However, both vagal stimulation and methacholine infusion significantly increased the relative number of neutrophils in the lavage compared to sham stimulated animals (21 +/- 11%, 13 +/- 4% and 4 +/- 1% respectively), but the extracorporeal resistor had no effect (4 +/- 2%). Our data suggests that prolonged bronchoconstriction per se may induce an influx of neutrophils into the airway lumen of the guinea-pig.