HYPERTONIC SALINE RESUSCITATION REDUCES NEUTROPHIL MARGINATION BY SUPPRESSING NEUTROPHIL-L SELECTIN EXPRESSION

Hypertonic saline (MS) reduces hemorrhage-induced lung injury by suppr essing the neutrophil oxidative burst and reducing lung neutrophil inf lux. This study investigated whether this is caused by the effects of HS on endothelial adhesion molecule expression, the production of chem oattractants in the lung, or a direct effect of HS on neutrophil selec tin expression. Methods: BALB/c mice mere made to hemorrhage to 40 mm Mg for 1 hour and resuscitated with shed blood and either 4 mL/kg 7.5% HS or two times the shed blood volume of lactated Ringer's solution ( LRS), Neutrophil L selectin expression was determined by flow cytometr y, total neutrophil counts were obtained by differential staining, and pulmonary endothelial P and E selectin expression was evaluated by im munohistochemistry, Chemoattractants in lung lavages were determined w ith a modified Boyden chamber migration assa. Results: Chemotactic act ivity of lavage fluid of MS-treated animals was not significantly diff erent from that of LRS-treated animals, and endothelial P and E select in expression was not altered by HS resuscitation, Neutrophils of MS-t reated animals, however, expressed significantly less L selectin than those of LRS-treated mice, Concomitantly, circulating neutrophil count s of LRS-treated animals were significantly decreased compared with th ose of MS-treated mice. Conclusion: HS had little effect on endothelia l selectin expression and chemoattractant production in the lung, HS s ignificantly decreased neutrophil L selectin expression, however, This suggests that MS resuscitation may reduce lung injury by preventing n eutrophil L selectin expression and endothelial adhesion.