Mechanisms of High Flow Induced Vasculopathy

描述（由申请人提供）：血流增加引起一系列血管反应，其中最早的反应是增殖性的，主要是内皮介导的，随后是肌原性张力的发展（有助于将血流恢复到基线）和对激动剂的反应性增强。这种对收缩剂反应增强的机制尚不完全清楚，但可能涉及内皮细胞和血管平滑肌细胞中离子通道介导的信号转导。我们已经开发了一种高血流模型（由主动脉-肺吻合术创建），该模型导致临床肺动脉高压的新内膜增殖特征和早期增强的反应性，其反应性似乎依赖于内皮细胞和l型钙通道。我们的初步数据表明，持续的血流导致NOS中电压门控钙通道的表达增加和功能障碍，这可能有助于增强分流动脉的反应性。我们假设，随着血流增加，内皮源性eet的合成急剧增强，增加了l型钙的开放，并减少了下邻pavsm中钙激活的K通道的开放。该资助的具体目的有三个：(i)我们将确定血管平滑肌细胞中的内皮第二信使信号通路（包括PLC、EETs、NOS和Ca(L)和KCa离子通道）对暴露于高流量或基线流量的PAs的张力和反应性的贡献。(2)我们将表征血流诱导的pa中eNOS表达水平的变化，以及肺动脉血管平滑肌细胞中Ca(L)和KCa型离子通道的表达。(3)我们将研究血流诱导的内皮第二信使信号级联PLC、EETs、NOS、pasmc中Ca(L)和KCa通道门控的活性变化，以及EETs对分流与非分流肺动脉PAVSMCs中[Ca2+]i的影响。这些研究应该提供关于高血流诱导的血管病变的细胞机制的有价值的信息，这种情况使许多临床上重要的情况复杂化，如先天性心脏缺陷的修复，肺切除术等。

DESCRIPTION (provided by applicant): Increased flow induces a series of vascular responses, the earliest of which are prodilatory and largely endothelial mediated, followed by the development of myogenic tone (which serves to return blood flow towards baseline) and enhanced reactivity to agonists. The mechanisms, which underlie this heightened response to contractile agents, are incompletely understood, but likely involve ion channel-mediated transduction of signals in endothelial and vascular smooth muscle cells. We have developed a model of high flow to isolated lung lobes of young pigs (created by an aorto-pulmonary anastomosis) which results in neointimal proliferation characteristic of clinical pulmonary hypertension and early enhanced reactivity which reactivity appears to be endothelial and L-type calcium channel dependent. Our preliminary data suggest that sustained flow results in increased expression of voltage-gated calcium channels and dysfunctions in NOS which may contribute to enhanced reactivity of shunted arteries. We hypothesize that acutely enhanced synthesis of endothelial-derived EETs increases opening of L-type calcium and decreases the opening of calcium activated K channels in subjacent PAVSMs following increased flow. The specific aims of the grant are threefold: (i) We will identify the contribution of the endothelial second messenger signaling pathways including PLC, EETs, NOS and Ca(L) and KCa ion channels in vascular smooth muscle cells to the tone and reactivity of PAs exposed to high or baseline flows. (2) We will characterize flow-induced changes in expression of eNOS levels in PAs as well as expression of Ca(L) and KCa type ion channels in pulmonary artery vascular smooth muscle cells. (3) We will examine flow-induced changes in activity of endothelial second messenger signaling cascades PLC, EETs, NOS, gating of Ca(L) and KCa channels in PAVSM, and effect of EETs on [Ca2+]i in PAVSMCs of shunted versus non-shunted pulmonary arteries. These studies should yield valuable information about cellular mechanisms which underlie high flow induced vasculopathy, which conditions complicate a number of clinically important conditions such as repair of congenital heart defects, pneumonectomies, and others.