The research with genetic engineering regarding the circulatory regulation of spinal microvasculature and the effects of anesthetics

取大鼠或小鼠脊髓制作厚150μm的脊髓切片。切片用对照液以1.5ml/m in的速度连续灌流，以93%O2+7%CO2(PCO2=40℃，pH=7.4，37 mm Hg)鼓泡。脑实质内微动脉(内径5.0~10.0μm)位于神经元组织内，用实时计算机视频显微镜连续监测其内径。视频显微镜设备由倒置显微镜组成。实质小动脉的图像被传输到摄像机(C6790-81，奥林巴斯，日本东京)，并通过媒体转换器(Physio-Tech，日本东京)显示在计算机上。将脊髓微血管管腔内径的变化记录在计算机图像文件中，并用图像软件进行分析。在前列腺素F_2α&Gt；(0.5μM)收缩过程中，高碳酸血症(10%CO2产生的PCO_2=50 mm Hg)引起实质内小动脉扩张。加入乙酰胆碱(0.1μM)后，正常小鼠脊髓切片上的小动脉扩张，而神经元型一氧化氮合酶基因敲除小鼠脊髓切片上的小动脉扩张不明显。麻醉药对上述血管扩张反应的影响正在研究中。这些结果表明，在脊髓微动脉中，二氧化碳作为血管扩张物质发挥作用，神经元型一氧化氮合酶参与包括乙酰胆碱在内的生理药物诱导的脊髓血管扩张反应。

Spinal slices (150 μm thick) were prepared from the rat or mouse spinal cords. Slices were continuously superfused with control solution at the flow rate of 1.5 ml/min, bubbled with 93% O_2 + 7% CO_2 (PCO_2 = 40 mmHg, pH = 7.4, 37℃). An intraparenchymal arteriole (5.0-10.0 μm in internal diameter) was located within the neuronal tissue, and its internal diameter was continuously monitored with the live computerized videomicroscopy. The videomicroscopy equipment consisted of an inverted microscope. The image of a parenchymal arteriole was transmitted to video camera (C6790-81, Olympus, Tokyo, Japan) and displayed on a computer via a media converter (Physio-Tech, Tokyo, Japan). Changes of intraluminal diameter in spinal microvessels were recorded on computer image files and then analyzed using the image software.During contraction to prostaglandin F_<2α> (0.5 μM), hypercapnia (PCO_2 = 50 mmHg produced by 10% CO2) induced dilation of intraparenchymal spinal arterioles. Addition of acetylcholine (0.1 μM) also induced dilation of these arterioles in the spinal slice from normal mice, whereas this concentration of acetylcholine did not induce dilation of arterioles in the slice from neuronal nitric oxide synthase knockout mice. Effects of anesthetics on above vasodilator responses are under investigation.These results suggest that in spinal microarterioles, carbon dioxide play a role as a vasodilator substance and that neuronal nitric oxide synthase contributes to spinal vasodilator responses induced by physiological agents including acetylcholine.