ENDOTHELIN EFFECTS ON RETINAL CELLS AND BLOOD FLOW

激素调节视网膜血管循环的机制是 不清楚 最近，一种新的有效的血管活性激素内皮素， 已经被描述并测序了。 的 内皮素（ET）家族由至少三种激素组成， 对血管平滑肌细胞的血管收缩作用。 最近， 有证据表明，ET可能在调节视网膜的 自它在视网膜和视网膜血管中被发现以来， 细胞 由于视网膜毛细血管细胞具有高亲和力和特异性， 兔眼玻璃体注射ET-1受体， 视网膜血管收缩。 我们最近发现， 胰岛素通过自身受体调节ET-1 mRNA的表达 通过一种新的机制。 此外，我们已经证明，视网膜 周细胞具有95和65 kD的ET-1受体，而平滑肌细胞具有95和65 kD的ET-1受体。 只有60 kD的受体 最后，利用视频图像分析 荧光素血管造影，玻璃体内推注1 × 10 - 19 M的 ET-1引起视网膜动脉和小动脉收缩， 增加视网膜循环时间长达20分钟后输注。 我们建议研究以下三个具体目标： 确定视网膜和主动脉内皮细胞中ET-1的调节， DNA水平的胰岛素; B）表征高葡萄糖水平的作用 和蛋白激酶C在调节ET-1表达中的作用; 内皮素-1在视网膜、主动脉和肾血管内皮细胞中的表达 糖尿病大鼠的异常。2a）表征、纯化和测序 视网膜周细胞中ET-1的受体; B）测定视网膜周细胞中ET-1的生物学活性。 内皮素-1在周细胞中的作用 甘油二酯、IP 3、蛋白激酶C和钙调蛋白。3)评价 内皮素对糖尿病视网膜循环的生理作用 非糖尿病大鼠。 从这些研究中，我们将能够了解ET的 在遗传、生物化学、细胞和免疫系统中的表达和作用方式， 生理水平，特别关注其在发展中的作用， 糖尿病视网膜血管功能障碍

The mechanisms by which hormones regulate retinal vascular circulation are not clear. Recently, a new and potent vasoactive hormone, endothelin, has been described and sequenced from vascular endothelial cells. The endothelin (ET) family consists of at least three hormones which have a vasoconstrictive effect on vascular smooth muscle cells. Recently, evidence has indicated that ET probably has a role in regulating retinal circulation since it has been identified in the retina and retinal vascular cells. Since retinal capillary cells have high affinity and specific receptor for ET-1, ET injected into rabbit vitreous was shown to induce vasoconstriction of retinal vessels. We have recently shown that the expression of ET-1 mRNA is regulated by insulin via its own receptor through a novel mechanism. In addition, we have shown that retinal pericytes have ET-1 receptors of 95 and 65 kD whereas smooth muscle cells only have the 60 kD receptor. Lastly, using image analysis of video fluorescein angiogram, the intravitreal bolus injection of 1 x 10 19 M of ET-1 induced vasoconstriction of retinal arteries and arterioles and increased retinal circulation times for as long as 20 min after infusion. We are proposing to study the following three Specific Aims: la) to determine the regulation of ET-1 in retinal and aortic endothelial cells by insulin at the DNA level; b) to characterize the role of high glucose level and protein kinase C in regulating ET-1 expression; c) to correlate the expression of ET-1 in the retina, aorta and kidney with vascular abnormalities in diabetic rats. 2a) To characterize, purify and sequence the receptors of ET-1 in retinal pericytes; b) to determine the biological effects of ET-1 in pericytes on the stimulation or activation of diacylglycerol, IP3, protein kinase C and calponin. 3) To evaluate the physiological actions of ET on retinal circulation in diabetic and non-diabetic rats. From these studies, we will be able to understand ET's expression and mode of action at the genetic, biochemical, cellular and physiological levels with special focus on its role in the development of retinal vascular dysfunctions in diabetes.