The effect of severe generalized edema on respiratory system mechanics is not well described. We measured airway pressure, gastric pressure, and four vertical pleural pressures in 13 anesthetized paralyzed pigs ventilated in the upright position. Pressure-volume relationships of the respiratory system, chest wall, and lung were measured on deflation from total lung capacity to residual volume and during tidal breathing both before (control) and 50 min after one of two interventions. In one series of experiments, a volume equal to 15-20% of the pig's body weight was infused intravenously. In a second series, a balloon was placed in the peritoneal space to distend the abdomen to the same gastric pressures as achieved in the first series. Measurements were compared before and after either abdominal balloon inflation or volume infusion. Volume infusion increased the pleural pressure in dependent lung regions, decreased both total lung capacity (34%) and functional residual capacity (62%) (both P less than 0.05), and markedly shifted the respiratory system and chest wall pressure-volume curves to the right, but it only moderately affected the lung deflation curve. Tidal compliances of the respiratory system, chest wall, and lung decreased 36, 31, and 49%, respectively (all P less than 0.05). The effect of abdominal balloon inflation on respiratory system mechanics was similar to that of volume infusion. We conclude that infusing large volumes of fluid markedly alters chest wall mechanics, mainly by causing abdominal distension that prohibits descent of the diaphragm.

Genes whose expression was up-regulated in low boron (B)-acclimated tobacco BY-2 (Nicotiana tabacum L. cv. Bright Yellow 2) cells, which had been selected under a low supply of B, were screened by the cDNA differential subtraction method. Thirteen genes were identified, including early salicylate-inducible glucosyltransferase, glutamine synthetase, glutathione S-transferase, and a pathogenesis-related protein, which might constitute a rescue system for oxidative damage. This indicates that B deficiency might impose cellular redox imbalance on the cells. Two of the 13 genes were induced within 30 min of B removal in the parent cells, indicating fast signal transfer from the cell walls to the cytoplasm.

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