MICROELECTRODE AND BLOOD FLOW STUDIES IN OPTIC NERVE

这个项目的长期目标是实现更好的 对视神经血流量控制机制的认识 头部(ONH)，以及可能导致血流受损和 营养支持。为了达到这一目标，体内实验研究 将在麻醉猫的ONH中使用微电极进行 测量组织氧、氢离子(PH)和钾离子。ONH血 流量测量将采用激光多普勒流量计(LDF)这一新技术 该仪器已成功应用于医院的血流量测量。 皮肤、骨、鼻和肠粘膜、肾、脑、 周围神经和其他组织。一种改进型激光测距系统 我们的实验室使用红外线激光二极管，允许血液流动 测量将在深色适应的眼睛中进行。我们的实验室现在可以 将LDF与电化学微传感器相结合，提供独特的 功能强大的局部组织微环境检测实验系统 具有出色的空间和时间分辨率。中国的空间变异 预计化学微环境(PO2、pH、K+)是由于光学 神经具有复杂的血管系统，其血流来源与 视网膜和脉络膜循环。将进行实验，以 获得P02、pH和K+的组织分布和梯度 正常的、对照的(非应激的)生理条件。中的更改 将测量化学微环境是否发生生理变化 情况，包括眼压升高和神经功能增强 由闪烁的光刺激引起的活动。ONH血流量，P02，pH， 和K+对包括高氧在内的瞬时生理应激的反应， 将测量低氧和高碳酸血症作为对照和改变 条件。将测量血流量、P02、pH和K4+的变化 在黑暗中适应控制和改变生理条件。 与对照条件相比，氧化代谢的相对变化 根据稳态血流量和术后P02差值计算 高于生理压力。这些研究中的许多从来没有 之前尝试过。预计结果将与青光眼相关， 糖尿病视网膜病变和其他致病因素 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，这可能最终提供 改良的非侵入性临床仪器用于早期检测 人类的病理变化。

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.