Difference and significance of SP-B content in alveolar lavage fluid and other related indexes at same time after blast injury in rabbit lungs with different maturities

Abstract

Objective To explore the difference of SP-B content in alveolar lavage fluid (ALF) between immature lung and mature lung at the same time point after lung blast injury, and investigate the significance and pathophysiological characteristics of related indexes. Methods The experimental animals (both sexes) included 40 healthy young New Zealand rabbits, weighting 442.10±55.30 g (young rabbit group), and 40 healthy New Zealand rabbits, aged 24 weeks, weighting 2 018.15±145.80 g (adult rabbits group). The experimental model was established under different driving pressures to ensure that the severity of injury was consistent (drive pressure: 4.5 MPa for young rabbit group and 4.0 MPa for adult rabbit group). After injury, the ALF content of SP-B was measured with ELISA at the immediate (0), 2, 4, 6, 12, 24, 48 and 72 h after injury, and the lungs were observed for gross anatomy and pathological changes. The tissue water content and other physiological indicators were determined at the same time. Results The severity of lung injury was consistent between the 2 groups (P>0.05). The SP-B concentration in the young rabbit group was lower than that in the adult rabbit group at all time points (P < 0.05); the alveolar wall rupture and injury were more commonly observed in the young rabbits, and the alveolar interstitial hemorrhage and inflammatory cell infiltration were more common in the adult rabbits; the lung water content at 2 h after injury (82.68±0.58 vs 81.06±0.34) and the oxygen saturation at 0.5 h after injury (75.00±18.52 vs 42.20±21.84) were higher in young rabbits group than adult rabbits group (P < 0.05). The percentage of neutrophils in the young rabbits group at 6 (36.92±16.01 vs 60.30±12.09), 12 (31.42±11.30 vs 46.40±14.15), 24 (29.48±4.76 vs 35.52±9.77) and 48 h (25.70±11.66 vs 37.68±9.11) after injury were lower than adult rabbits group (P < 0.05). Conclusion Compared with mature lungs of adult rabbits after lung blast injury, the immature lungs of young rabbits recover faster and have milder inflammatory reaction, but the SP-B content is lower, the synthesis and secretion function recover slowly, which may lead to the recovery of respiratory function slow. Our results may be used to guide the treatment for injury in immature and mature lungs.

Keywords

• blast lung injury
• immature lung
• pulmonary surfactant-associated protein b
• pathophysiological characteristics