| Background and objective:Acute kidney injury (AKI) induced by renal ischemia/reperfusion (rI/R) is a frequent complication in perioperative period, and is a crucial contributor to high mortality. AKI rarely occurs in isolation, and often contributes to distant-organ pathological damage and dysfunction. Due to its large microcapillary network, the lung is highly susceptible to damage caused by circulating pro-inflammatory or pro-apoptosis mediators from kidney inflicted with ischemia-reperfusion. While ALI induced by AKI becoming a hotspot of research, there is no more useful therapeutic strategies which is proven to change the outcomes of patients.Dexmedetomidine (DEX) is a highly selective α2 adrenergic agonist that exhibits a broad pattern of actions. Previous studies have demonstrated that DEX has protective effects on organ I/R insults. In rI/R injury, DEX may reduce lung edema and lower MPO activity. Meanwhile, in hippocampal slices subjected to oxygen glucose deprivation (OGD), DEX exhibits a preconditioning effect against ischemic injury through increasing phosphorylation of focal adhesion kinase (FAK) via stimulation of α2 adrenoceptors.FAK is a cytoplasmic tyrosine protein kinase, participates in peripheral actin cytoskeletal rearrangement and cell-cell, cell-matrixes junctional complex that combine to decrease vascular permeability. In this study, we established the ALI model induced by rI/R, detected the effects of DEX on pulmonary hyper-permeability induced by rI/R, detected the effects of DEX on FAK expression and phosphorylation in pulmonary endothelial cells, and explored the role of FAK in kidney-lung protective effect. We confirmed that DEX could attenuate remote pulmonary vascular hyper-permeability induced by rI/R via FAK mediated α2-adrenoreceptor activation.Methods:1. Effects of DEX and rI/R mice serum on pulmonary vascular endothelium permeability.1.1 Establish the rI/R model in C57BL/6J mice and collected rI/R mice serum.1.2 Recovery and culture C57BL/6J mice pulmonary microvascular endothelial cells (PMVEC).1.3 Detect the change of endothelial monolayers permeability induced by different concentration of rI/R serum.1.4 Detect the effects of DEX on endothelial monolayers permeability stimulated by rl/R serum.2. Effects of DEX on PMVEC FAK phosphorylation in rI/R condition.2.1 Detect the effects of DEX and rI/R serum on PMVEC FAK phosphorylation by immunofluorescence staining.2.2 Detect the effects of DEX and rI/R serum on PMVEC FAK express and phosphorylation by Western Blot.3. The effects of FAK phosphorylation on pulmonary microvascular hyper-permeability in rI/R condition.3.1 Detect the effects of FAK phosphorylation on pulmonary vascular permeability in rI/R condition in vivo.3.2 Detect the effects of FAK phosphorylation on endothelial monolayers permeability in rI/R condition in vitro.3.3 Detect the effects of FAK phosphorylation on endothelial F-actin in rI/R condition by Immunofluorescence Staining.Results:1. The trans-endothelial flux of albumin in the PMVEC monolayers, exposed to rI/R serum, were increased in serum concentration-dependent manner.2. DEX concentration-dependent attenuated pulmonary microvascular hyper-permeability caused by rI/R.3. rI/R serum increased both the phospho-tyrosine397FAK and the total FAK expression. 0.1 μM DEX caused the phospho-tyrosine397FAK increased and the total FAK decreased, this effect was partially reversed by α2-adrenoreceptor antagonist.4. In vivo or in vitro, the effect of DEX attenuated pulmonary microvascular hyper-permeability caused by rI/R decreased after a2-adrenoreceptor or FAK been inhibited. F-actin may participates in this protective effects.Conclusions:1. Established an in vitro model of ALI induced by AKI.2. DEX could attenuated pulmonary microvascular hyper-permeability in I/R condition via α2-adrenoreceptor.3. DEX caused the phospho-tyrosine397FAK increased and total FAK decreased, which might regulate the change of F-actin, suggesting the potential mechanism of DEX in protective effects. |
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