ALTERATIONS OF THE ENDOGENOUS SURFACTANT SYSTEM IN SEPTIC ADULT RATS

Sepsis is the most common factor leading to the acute respiratory dist ress syndrome (ARDS) and is associated with the highest mortality rate . It has been suggested that the pulmonary surfactant system is altere d and contributes to the lung dysfunction associated with ARDS. The ob jective of this study was to characterize the lung injury, specificall y the endogenous surfactant system in septic adult rats. Sepsis was in duced in male Sprague-Dawley rats by cecal ligation and perforation an d resulted in significant increases in heart rates, respiratory rates, and lactate levels along with positive blood cultures in septic anima ls compared with a sham control group. Two distinct septic groups were developed, a septic group and a sepsis with lung injury (septic + LI) group. The septic group had no significant differences in oxygenation compared with the sham group, whereas the septic + LI group had signi ficantly lower Pa-O2 and higher A-a gradient values compared to both t he sham and septic groups. The total surfactant pool size was signific antly lower in the septic + LI group compared with the sham group. The small surfactant aggregate to large surfactant aggregate ratio was si gnificantly lower in the septic group and was further reduced in the s eptic + LI group. There were also significantly higher levels of surfa ctant protein A (SP-A) in both septic and septic + LI groups compared to the sham group. These results demonstrated that the endogenous surf actant system was altered in systemic sepsis without lung dysfunction and is further altered when a lung injury is present.