title: Lobar variations in the mechanics of collateral ventilation in intact dog lungs.
abstract: Lobar differences in the mechanics of collateral ventilation were investigated in sublobar segments of intact dog lungs using a wedged-catheter technique. At functional residual capacity, the collateral time constant was longest in the left upper lobe and shortest in the lower lobes, with the remaining lobes having intermediate values. The time constant differences were due to lobar differences in effective segmental compliance. Atropine did not affect lobar variation in collateral ventilatory mechanics but decreased the collateral time constant as a result of a decrease in collateral resistance, indicating that airways within the segment and/or collateral pathways receive parasympathetic innervation. Slightly increasing the volume of the lobe occupied by the isolated segment decreased collateral resistance and increased effective segmental compliance but did not change the collateral time constant.
mesh_terms: D000818:Animals; D004285:Dogs; D008168:Lung / Q000502:physiology*; D008170:Lung Compliance; D008176:Lung Volume Measurements; D011669:Pulmonary Wedge Pressure; D012115:Residual Volume; D014692:Ventilation-Perfusion Ratio