MICROELECTRODE AND BLOOD FLOW STUDIES IN OPTIC NERVE

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， 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血液 流量将通过激光多普勒流量计（LDF）测量，这是一种新技术 其已经成功地应用于 皮肤、骨、鼻和肠粘膜、肾、脑、 周围神经和其他组织。 年开发的改进型LDF系统 我们的实验室使用红外激光二极管， 在黑暗适应的眼睛中进行测量。 我们的实验室现在可以 联合收割机LDF与电化学微传感器相结合， 强大的实验系统，用于检查局部组织微环境 具有出色的空间和时间分辨率。 的空间变化 化学微环境（PO2，pH值，K+），因为光学 神经具有复杂的脉管系统，其具有来自神经的血流的独立来源。 视网膜和脉络膜循环。 将进行实验， 获得组织分布和梯度的P02，pH值，和K+下， 正常、对照（无应激）生理条件。 变化 将测量化学微环境的生理改变 条件，包括眼内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+对瞬时生理应激的反应，包括高氧， 将测量低氧和高碳酸血症以控制和改变 条件 将测量ONH血流、P02、pH和K4+变化 在黑暗适应控制和改变的生理条件。 氧化代谢相对于对照条件的相对变化将是 根据稳态血流和P02差异计算， 在生理压力之上。 这些研究中有许多从未被 以前尝试过。 预期结果与青光眼相关， 糖尿病视网膜病变和其他病理条件， 视神经萎缩 从这些研究中获得的信息将 帮助解释LDF测量，这可能最终提供一个 用于早期检测的改进的非侵入性临床仪器 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.