LOWERING OF INTERSTITIAL FLUID PRESSURE WILL ENHANCE EDEMA IN TRACHEAOF ALBUMIN-SENSITIZED RATS

Interstitial fluid pressure (P-if) has recently been found to play an important role in edema formation in acute airway inflammation. Becaus e airway inflammation is important in the pathogenesis of asthma, P-if was measured in rat trachea after albumin challenge to rats previousl y sensitized to chicken egg albumin. In pentobarbital anesthesia (50 m g/kg intraperitoneally) sensitized rats received an intravenous infusi on of either saline or albumin, which circulated for 4 min. Circulator y arrest was then induced with saturated KCI intravenously to prevent further edema formation, which will increase P-if and thereby possibly cause an underestimation of an increased negativity of P-if. P-if was measured with sharpened glass capillaries (diameter 3-6 mu m) connect ed to a servo-controlled counter pressure system. P-if was -1.3 +/- 0. 4 mm Hg in controls and -5.8 +/- 0.5 mm Hg in sensitized rats (p < 0.0 1) after allergen challenge. Airway resistance was measured to verify the occurrence of airway narrowing and increased significantly in sens itized rats after allergen challenge but did not change in controls. T he experimental anti-inflammatory drug, alpha-trinositol (D-myo-inosit ol-l,2,6-trisphosphate, 10 mg), given before or after allergen challen ge abolished the increased negativity of P-if (p < 0.05), while hydroc ortisone (6.25 mg) had no effect. Thus, allergen challenge is associat ed with a lowering of P-if, which was abolished by alpha-trinositol.