Research On Protective Effects Of PGE₁ In Rats With Smoke Inhalation Pulmonary Injury

Objectives: To explore protective effects of PGE1 and its basic mechanism in rats with smoke inhalation pulmonary injury. Methods: 54 rats were randomly divided into three groups : control groups ( n = 8 ) , injury groups (n = 20) and PGE1 groups (n = 26) ; in PGE1 groups , aerosolized PGE1 were inhaled every 8 hours one time within the 0.5 ~ 48 hours after smoke inhalation injury . In injury groups and PGE1 groups , the indexes which we detected at the 6, 24 and 48 hours after injury were as follows : analysis of pathology in the lung , blood gas analysis , ratio of wet weight/dry weight(WTD) of the lung tissue , measure of WBC and PMN in the peripheral blood and analysis of AM, PMN and total protein (TP) in the BALF , the detections of MDA, SOD, NCK total NOS, iNOS, cNOS in the lung tissue and expression level of mRNA of TNF a in the cells of BALF . Results: (1) changes of pathology: diffuse congestion, hemorrhage, edema , infiltration of PMN were occurred in the lung tissue in injury groups, the extent and degree of these lesion were decreased after the treatment of inhalation of aerosolized PGE1. (2) In injury groups , the levels of PaO2 and PaO2/FiO2 were decreased and the levels of PaCO2 were increased gradually. It often induced metabolic acidosis and respiratory acidosis, but the inhalation of aerosolized PGE1 could prevent these tendency at the time of 6 hours , and elevated the levels of PaO2 and PaO2/FiO2 within the 24 ~ 48 hours. (3) TP and W/D levels of the injury groups were significantly higher than the control groups (P<0.05). In PGE1 groups, the levels of two indexes were decreased within the 24 ~ 48 hours.(4) In injury groups , the WBC , PMN and AM reached and maintained a high level within 6-48 hours. There were no significant changes of the WBC, PMN in the peripheral blood , but WBC and PMN in the HALF were decreased significantly in PGE1 groups , especially in the time of 48 hours. (5) Within 6~48 hours , the level of MDA were significantly higher than control groups , and the SOD maintained the low level in injury groups ; by the treatment of inhalation of aerosolized PGE1, the levels of MDA were significantly reduced in the time of 24 and 48 hours, but the levels of SOD could not recovered. (6) In injury groups and PGE1 groups , the NO,total NOS and iNOS in the lung tissue were significantly higher than control groups(P<0.05); there were a decreasing tendency of the NO and total NOS in PGE1 groups, especially , the levels of iNOS were lower than injury groups. cNOS levels fell in injury groups and PGEi groups , but there were an increasing tendency of the cNOS in PGEi groups. (7) In injury groups and PGE1 groups , TNF a -mRNA expression levels of cells in BALF were higher than control groups ; but the TNF a -mRNA expression decreased more significantly in PGE1 groups than injury groups in the time of 48 hours. Conclusion: (1) Protective effects of inhalation of aerosolized PGE1 include: to improve the blood gas indexes and depress vascular permeability, to lessen the lesion of pathology in the lung. (2) In our research, the mechanism of protective effects are as fellows : to reduce PMN sequestration and decrease the oxidation damage in the lung , to depress the expression of some cytokines such as TNF and NO.