Effect of β-adrenergic receptor agonists on pulmonary surfactant in the rats with acute lung injury

Objective To investigate the changes in pulmonary surfactant(PS)after acute lung injury (ALI) induced by oleic acid and the intervention effect of β-adrenergic receptor agonists.Methods Fifty-four Sprague-Dawley rats were randomly divided into three groups: ALI induced by oleic acid injection(OA group,n=18),therapy group treated by Isoprenaline hydrochloride injection(ISO group,n=18) and normal control treated by saline injection(NS group,n=18).Partial pressure of oxygen in artery (PaO 2),partial pressure of carbon dioxide in alveolar gas (PaCO 2),hydrogenion concentration (pH) and the serum surfactant protein A(SP-A)level were assayed at 1,2 and 4hours.After the animals were killed,the left lung was used for the measurements of wet/dry weight ratio(W/D) and histopathology,whereas we treated right lung with lavage and determined the total protein(TP),total phospholipid(TPL),disaturated phosphatidylcholine(DSPC)and SP-A in the bronchoalveolar lavage fluid (BALF).Results TPL,DSPC/TPL and SP-A of OA group in the BALF were significantly and progressively decreased ( P 0 01) from 1 hour after oleic acid injection, whereas W/D,TP and serum SP-A concentration were progressively increased( P 0 05 or P 0 01), compared with NS group.The values of SP-A in the BALF were negatively correlated with those in the serum of OA group at same time points.TPL,DSPC/TPL and SP-A of ISO group in the BALF were significantly increased, whereas W/D,TP and serum SP-A were significantly decreased( P 0 05 or P 0 01), compared with OA group at the same time points.Conclusions The PS inactivation may be the important internal causes during the course of ALI induced by oleic acid injection,β-adrenergic receptor agonists may lessen the development of ALI induced by oleic acid injection to some extent.