Mechanisms of High Flow Induced Vasculopathy

描述（由申请人提供）：血流增加诱导一系列血管反应，其中最早的反应是前扩张性的，主要是内皮介导的，随后是肌源性张力的发展（用于使血流恢复至基线）和对激动剂的反应性增强。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。我们已经开发了一个模型的高流量，以孤立的肺叶的年轻猪（创建一个肺动脉-肺吻合），导致新生内膜增殖的特点，临床肺动脉高压和早期增强的反应性，反应似乎是内皮和L型钙通道依赖性。我们的初步数据表明，持续的血流导致电压门控钙通道表达增加和NOS功能障碍，这可能有助于增强分流动脉的反应性。我们推测，急性增强的内皮源性内皮素的合成增加开放的L型钙和减少开放的钙激活的K通道，在subjobalPAVSMs后增加流量。该基金的具体目标有三个：（i）我们将确定血管平滑肌细胞中内皮第二信使信号通路（包括PLC、E2、NOS和Ca（L）和KCa离子通道）对暴露于高流量或基线流量的PA的张力和反应性的贡献。(2)我们将表征PA中eNOS水平表达以及肺动脉血管平滑肌细胞中Ca（L）和KCa型离子通道表达的流动诱导的变化。(3)我们将检测血流诱导的内皮第二信使信号级联PLC、EkB、NOS活性的变化，PAVSM中Ca（L）和KCa通道的门控，以及EkB对分流与非分流肺动脉PAVSMC中[Ca 2 +]i的影响。这些研究应该产生关于高流量诱导的血管病变的细胞机制的有价值的信息，所述血管病变使许多临床上重要的病症复杂化，例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.