Effect Of Angiotensin Ⅱ And Its Receptors On LPS-induced Rat Acute Lung Injur

BackgroundThe renin-angiotensin system is thought to be involved in development and progression of vascular endothelium inflammation, thereby contributing to vascular endothelium injury. Angiotensin â…¡ (Ang â…¡) is the main effector and media of the most function of renin-angiotensin system. Lipopolysacchride (LPS)-induced sepsis is the leading cause of acute lung injury (ALI). It is well known that LPS induces increasing microvascular endothelial permeability which produces pulmonary edema, it also stimulates the circulating and local Ang â…¡. So, we hypothesized that, Ang â…¡ might play a role in LPS-induced ALI both in vivo and in vitro. Since the pulmonary microvascular endothelial cell to be initially injury during every causes induced ALI, in order to elucidate the role of Ang â…¡ in rat pulmonary microvascular endothelial cells (RPMVEC), in the first part of our study, we examined the expression and functional significance of Ang â…¡ receptors in normal and LPS/Ang â…¡ treated RPMVEC, and tried to study further the functions of Ang â…¡ and its receptors in LPS-induced ALI in the second part of our study. Contents of studyOur study was carried on successfully both in established LPS-induced rat ALI model and in cultured RPMVEC. In the first stage, the expressions of Ang â…¡ typel(AT1) and Ang â…¡ type 2 (AT2) receptors in cultured RPMVEC were identified by the reverse transcription-polymerase chain reaction (RT-PCR) technique, Western blot and ¹²⁵I-labeled [Sar¹,Ile⁸] Ang â…¡ binding assays. The RPMVEC were treated with LPS/ Ang â…¡ for different concentrations and time points respectively. The changes of mRNA and protein levels of ATI and AT2 receptors were determined. In the second stage,...