Journal of applied physiology
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The rapidity with which lung growth was initiated following pneumonectomy was investigated using rats (330 g) in which lung weight-to-body weight ratio and lung cell size had stabilized. Following removal of the left lung, right lung weight increased from 823 to 1.161 mg within 7 days. Right lung weight in sham-operated animals did not change significantly. ⋯ Synthesis of lung proteins, estimated during 120 min of perfusion in situ, was elevated 25% on day 3. Incorporation of [3H]thymidine into DNA increased somewhat on day 2 and was elevated fourfold on day 3, corresponding with the initial accumulation of total DNA within the lung. These observations suggested that increased cell size may accompany early compensatory growth following pneumonectomy, but that the major portion of the response involved cellular hyperplasia.
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The effects of the mode of reinflation and of the duration of prior collapse on the development of unilateral pulmonary edema following reexpansion of collapsed lung were studied in a rabbit model simulating the human syndrome of "reexpansion pulmonary edema." The right lungs of rabbits were maintained in an atelectatic state for 0.5 h to 8 days, by injection of air into the pleural space. Reexpansion was achieved in 2 h by application of positive pressure to the airway while a chest tube was connected to underwater seal, or by application of negative pressure (-20 to -100 Torr) to a screened window in the partietal pleura. ⋯ The incidence of unilateral pulmonary edema increased as the duration of prior collapse was increased (85% after 7--8 days; 17% after 3 days; and 0% after 0,5 h) when reinflated with -100 Torr applied to the pleural window. Although the incidence was less, it also occurred following the use of pleural window pressure less negative than -100 Torr, and after reinflation by positive airway pressure.
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The intrapulmonary distribution of inspired gas (ventilation/unit lung volume, VI), functional residual capacity (FRC), closing capacity (CC), and the slope of phase III were determined in five awake and five anesthetized-paralyzed volunteers who were in the prone position with the abdomen unsupported. After induction of anesthesia-paralysis, FRC was less in four of five subjects and CC was consistently less. ⋯ The normalized slope of phase III decreased consistently with induction of anesthesia-paralysis, but the vertical distribution of a 133Xe bolus inhaled from residual volume was not different between the two states. The data of the study are compatible with 1) a pattern of expansion of the respiratory system during anesthesia-paralysis and mechanical ventilation different than that during spontaneous breathing and 2) a more uniform intraregional distribution of inspired gas and/or a different sequence of emptying during anesthesia-paralysis.
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We examined the influence of stellate ganglion stimulation, hypoxia, and the infusion of norepinephrine, PGF2alpha, serotonin, and histamine on the longitudinal distribution of vascular resistance and intravascular pressures in an isolated left lower lobe of the dog lung using the low-viscosity bolus technique. Sympathetic stimulation, norepinephrine, serotonin, PGF2alpha, and hypoxia increased total pulmonary vascular resistance by increasing the resistance, primarily on the arterial or upstream side of the volume midpoint, whereas histamine increased the resistance near the venous end of the lobar vascular bed. Hypoxia increased the volume upstream from the site of maximum resistance, suggesting that the larger lobar arteries were distended by the elevated lobar artery pressure. Sympathetic stimulation, norepinephrine, PGF2alpha, and serotonin, on the other hand, had little effect on the volume upstream from the maximum resistance, suggesting that these vasomotor stimuli prevented distension of the larger arteries.
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Comparative Study
Lung volumes in man immersed to the neck: dilution and plethysmographic techniques.
Previous studies of lung volumes during immersion have utilized dilution techniques for residual volume. We have compared lung volumes obtained by the use of a dual inert gas dilution technique with those determined by the Boyle's law technique in a plethysmograph designed to allow measurements in air and submersed to the neck in water. Both techniques gave similar results dry, but during immersion the dilution residual volume (RV) was 0.200 liter (16%) lower than the plethysmographic value (P greater than 0.001), which suggests that there is a significant amount of gas trapping during immersion due to breathing at low lung volumes and the central shift of blood. The unchanged RV due to hydrostatic force on the chest wall is balanced by the tendency to increase RV due to vascular congestion, which increases closing volume and stiffens the lung to compression.