ENDOTHELIN EFFECTS ON RETINAL CELLS AND BLOOD FLOW

说明(改编自申请人的摘要)： 建议理解ET及其受体在调节中的作用 正常和糖尿病状态下的视网膜血流动力学 培养的视网膜血管细胞。自第一个报告显示 视网膜周细胞中ETA受体的存在及其调控 胰岛素诱导的ET-1、ET-1和ET-3的表达 视网膜血管细胞的活动。调查员的结果是 证实ET-1通过ETA受体是一种主要的调节因子 正常动态期和高氧期视网膜的血管张力 糖尿病视网膜病变的早期阶段。血管收缩功能增强 在这些状态下观察到的是由于ET-1的过度表达或 内皮素转换酶(ECEs)对其加工的促进作用 视网膜。最近，申请人证明胰岛素可以降低ET-1 在周细胞和平滑肌细胞中的基因表达可以部分 解释胰岛素的体内血管扩张作用。在信号灯处 信号转导水平、ET-1和血管紧张素对磷脂酶C的影响 (PLC)-蛋白激酶C(PKC)激活与酪氨酸激酶级联反应 涉及周细胞和平滑肌细胞中的MAPK。调查员 最近发现血管紧张素和ET-1也可以激活G蛋白 相关的磷脂酰肌醇3-激酶(PI-3-激酶)，从而识别 ET-1全新的信号转导途径。最后，发现 高血糖可钝化ET-1‘S对PLC激活的影响已证实 平滑肌细胞和肾小球系膜细胞。调查员 提出：(1)研究ET-1在血管内皮细胞中的表达和表达。 胰岛素、氧分压、血管紧张素对视网膜血管细胞的调节 和高血糖；(2)识别各种信号转导途径 ET-1在视网膜周细胞和血管内皮细胞中的作用 G蛋白相关的PI3K的激活及其相互关系 这些生物作用的途径，如钙流动、一氧化氮的产生和 DNA合成；(3)测定ET-1的表达和作用 体内ET-3及其受体对正常视网膜血流动力学的影响 糖尿病。

DESCRIPTION (Adapted from applicant's abstract): The purpose of the proposal is to understand the role of ET and its receptors in modulating retinal hemodynamics in the normal and diabetic state in vivo and in cultured retinal vascular cells. Since the first report showing the existence of ETA receptors in the retinal pericytes and the regulation of ET-1 expression by insulin, ET-1 and ET-3 have been shown to have many actions in retinal vascular cells. The investigator's results have established the fact that ET-1 via ETA receptor is a major regulator of vascular tone in the retina during normal homeostasis and hyperoxia and in the early stages of diabetic retinopathy. The increased vasoconstriction observed in these states are due to either overexpression of ET-1 or increase in its processing by endothelin converting enzyme (ECE) in the retina. Recently, the applicant has shown that insulin can decrease ET-1 gene expression in pericytes and smooth muscle cells which could partially explain the in vivo vasodilatory effect of insulin. At the signal transduction level, ET-1 and angiotensin can affect phospholipase C (PLC)-protein kinase C (PKC) activation and the tyrosine kinase cascade involving MAP kinase in pericytes and smooth muscle cells. The investigator has recently found that angiotensin and ET-1 can also activate a G-protein associated phosphatidylinositol 3-kinase (PI 3-kinase), thereby identifying a whole new signal transduction pathway for ET-1. Lastly, the finding that hyperglycemia can blunt ET-1's effect on PLC activation has been confirmed by smooth muscle cells and mesangial cells as well. The investigator proposes: (1) to characterize the expression and processing of ET-1 in retinal vascular cells as regulated by insulin, oxygen tension, angiotensin and hyperglycemia; (2) to identify the various signal transduction pathways used by ET-1 in retinal pericytes and in smooth muscle cells specifically on the activation of G-protein-associated PI 3-kinase and the association of these pathways to biological actions such as calcium flux, NO production and DNA synthesis; and (3) to determine the expression and the effect of ET-1 and ET-3 and their receptors in vivo on normal retinal hemodynamics and in diabetes.