MICROELECTRODE AND BLOOD FLOW STUDIES IN OPTIC NERVE

视神经的微电极和血流研究

• 批准号: 3266647
• 负责人: DONALD G BUERK
• 金额: $ 8.55万
• 依托单位: PRESBYTERIAN MEDICAL CENTER OF PHILA
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-05-01 至 1995-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3266647
• 关键词: acidity /alkalinity; cats; dark adaptation; eye circulation; hypercapnia; hyperoxia; intraocular pressure; light intensity; optic nerve; oxygen microelectrode; oxygen tension; physiologic stressor; potassium; retina circulation; ultrasound blood flow measurement

The long term objective of this project is to achieve a better understanding of the mechanisms controlling blood flow to the optic nerve head (ONH), and factors which might lead to impaired blood flow and nutritional support. To meet this goal, in vivo experimental studies will be conducted in the ONH of anesthetized cats using microelectrodes to measure tissue oxygen, hydrogen ion (pH) and potassium ion. ONH blood flow will be measured by laser Doppler flowmetry (LDF), a new technology which has been successfully applied to blood flow measurements in the capillaries of skin, bone, nasal and intestinal mucosa, kidney, brain, peripheral nerves and other tissues. A modified LDF system developed in our laboratory uses infra-red laser diodes, permitting blood flow measurements to be made in dark adapted eyes. Our laboratory can now combine LDF with electro-chemical microsensors, providing a unique and powerful experimental system to examine local tissue microenvironment with excellent spatial and temporal resolution. Spatial variations in chemical microenvironment (PO2, pH, K+) are expected since the optic nerve has a complex vasculature with separate sources of blood flow from retinal and choroidal circulations. Experiments will be conducted to obtain tissue distributions and gradients for P02, pH, and K+ under normal, control (unstressed) physiological conditions. Changes in chemical microenvironment will be measured for altered physiological conditions, including elevated intraocular pressure and increased neural activity induced by flickering light stimulus. ONH blood flow, P02, pH, and K+ responses to transient physiological stresses including hyperoxia, hypoxia and hypercapnia will be measured for control and altered conditions. ONH blood flow, P02, pH, and K4+ changes will be measured during dark adaptation for control and altered physiological conditions. Relative changes in oxidative metabolism from control conditions will be calculated from steady state blood flow and P02 differences after the above physiological stresses. Many of these studies have never been attempted before. Results are expected to be relevant to glaucoma, diabetic retinopathy and other pathological conditions which contribute to optic nerve atrophy. Information derived from these studies will assist in interpreting LDF measurements, which may eventually provide an improved, noninvasive clinical instrument for early detection of pathological changes in humans.

该项目的长期目标是实现更好的 了解控制视神经血流的机制 头部（ONH），以及可能导致血流受损的因素和 营养支持。 为了实现这一目标，体内实验研究 将使用微电极在麻醉猫的 ONH 中进行 测量组织氧、氢离子（pH）和钾离子。 ONH血 流量将通过激光多普勒流量计（LDF）进行测量，这是一项新技术 已成功应用于血流测量 皮肤、骨骼、鼻粘膜、肠粘膜、肾、脑的毛细血管， 周围神经和其他组织。 改进的 LDF 系统开发于 我们的实验室使用红外激光二极管，允许血液流动 在适应黑暗的眼睛中进行测量。 我们的实验室现在可以 将 LDF 与电化学微传感器相结合，提供了独特且 强大的实验系统来检查局部组织微环境 具有出色的空间和时间分辨率。 空间变化 化学微环境（PO2、pH、K+）是预期的，因为光学 神经具有复杂的脉管系统，其血流来源不同 视网膜和脉络膜循环。 将进行实验 获得 P02、pH 和 K+ 的组织分布和梯度 正常、受控（无压力）的生理状况。 变化 将测量化学微环境的生理变化 条件，包括眼内压升高和神经元增加 由闪烁光刺激引起的活动。 ONH 血流量、P02、pH、 和 K+ 对短暂生理应激（包括高氧）的反应， 将测量缺氧和高碳酸血症以进行控制和改变 状况。 将测量 ONH 血流量、P02、pH 和 K4+ 变化 在暗适应控制和改变生理条件期间。 与对照条件相比，氧化代谢的相对变化将是 根据稳态血流量和 P02 差异计算 高于生理压力。 其中许多研究从未被 之前尝试过。 预计结果与青光眼相关， 糖尿病视网膜病变和其他导致的病理状况 以致视神经萎缩。 从这些研究中获得的信息将 协助解释 LDF 测量结果，最终可能提供 改进的非侵入性临床仪器，用于早期检测 人体的病理变化。