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Effects of meconium aspiration in isolated perfused rat lungs
Author(s) -
Wisniewski Wlodzimierz M.,
Zagariya Alexander M.,
Pavuluri Narendra,
Srinivasan Harry,
Shankarao Shan,
Vidyasagar Dharmapuri
Publication year - 2005
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.20123
Subject(s) - medicine , meconium , meconium aspiration syndrome , lung , hypoxia (environmental) , saline , anesthesia , pulmonary artery , respiratory system , pulmonary compliance , fetus , chemistry , biology , pregnancy , genetics , organic chemistry , oxygen
Our objective was to study meconium‐induced lung injury in isolated perfused rat lungs exposed to anoxia. Our working hypothesis was that meconium‐induced lung injury is independent of preexisting hypoxia, and that hypoxia will increase severity of lung injury observed after meconium aspiration. We comparde five different groups of animals (n = 5) for pulmonary arterial pressure (PAP), weight lung changes, and TNFα expression. Group I had lungs instilled with 4 ml of normal saline. Group II had lungs exposed to 5 min of anoxia. Group III had lungs instilled with 4 ml of 30% filtered human meconium. Group IV had lungs exposed to 5 min of anoxia and then instilled with 4 ml of 30% filtered human meconium. Group V had lungs instilled with 4 ml of 30% unfiltered human meconium. Our subjects were adult Sprague‐Dawley rats. The isolated rat lung model was prepared according to Levey and Gast (J Appl Physiol 1966;21:313–316). Lungs were ventilated with room air. Anoxia was caused by the use of N 2 . The pulmonary artery was cannulated, and pulmonary arterial pressure and lung weight were measured. Lung weight and pulmonary arterial pressure were monitored for 120 min, and TNFα levels were measured in effluent at 15, 30, 60, and 120 min. Experiments were done at the Michael Reese Hospital (Chicago, IL). At the end of the experiment, PAP reached its highest values in group V (10.0 ± 1.7 mmHg). Final PAPs in groups I–IV were: 4.85 ± 0.3, 4.99 ± 0.4, 5.93 ± 0.3, and 7.25 ± 0.51 mmHg, respectively). Lung wet weight increased significantly only in groups IV and V vs. group I; at 120 min, they were: 0.96 ± 0.3 g, P < 0.01, and 1.5 g ± 0.2 g, P < 0.01, respectively. TNFα levels did not change significantly over time in group I. TNFα is a marker as well as proprietor of pulmonary inflammatory response. TNFα reached its highest levels in groups IV and V: 595 and 753 pg/ml at 120 min, respectively. In conclusion, a short episode of anoxia prior to meconium aspiration may increase lung sensitivity to meconium‐induced lung injury. This effect may be moderated by the TNFα present in the pulmonary circulation. Pediatr Pulmonol. 2005; 39:368–373. © 2005 Wiley‐Liss, Inc.