CALCIUM: BLOOD-BRAIN BARRIER AND CNS PATHOPHYSIOLOGY

临床低钙和高钙血症常伴有精神障碍。 中枢神经系统的功能，通常归因于异常 脑间质钙活性。与此明显矛盾的是 观点，已发表的实验室报告强调离子的独立性 脑脊液和脑间质液中的活性 在循环的血液中。这里提出的项目旨在 解决这一冲突有两个主要目标：a.确定 脑间质钙活性对血浆的依赖程度 电离钙和总钙，以及血浆和脑pH值。B.确定 脑组织钙活性改变对脑组织的影响 功能。为了实现这些目标，钙的急性和慢性变化 活动水平将被诱导。呼吸和代谢的影响 碱中毒对血液和脑组织钙活性的影响 还将观察神经功能。此外，这些因素的相互作用 改变钙、镁、pH和PO2水平对神经元功能的影响 已评估。离子钙活度和pH值将在循环中测量 动脉血和脑间质中离子选择性 电极。氧分压将用极谱方法测量 微电极。此外，总钙、镁、pH、pO2，以及，在一些 实验，甲状旁腺激素水平，将在动脉样本中测量。 血。神经功能，包括脑电，癫痫阈值，诱发 电位、兴奋性和抑制性突触功能、神经元膜 特性将在完整的大脑和脊髓以及大脑中进行评估 组织切片在体外保存。

Clinical hypo- and hypercalcemia are frequently accompanied by disturbed function of the central nervous system, usually attributed to abnormal cerebral interstitial calcium activity. In apparent contradiction to this view, published laboratory reports emphasize the independence of ion activities in both cerebrospinal fluid and in cerebral interstitial fluid from that in circulating blood. The project proposed here is designed to resolve this conflict and it has two major goals: A. To determine the degree to which cerebral interstitial calcium activity depends on plasma ionized and total calcium, and on plasma and cerebral pH. B. To determine the effect of altered cerebral tissue calcium activity on cerebral function. To achieve these goals acute and chronic changes of calcium activity levels will be induced. The effects of respiratory and metabolic alkalosis on calcium activity in blood and in cerebral tissue and on neuronal function will also be observed. Further, the interactions of altered calcium, magnesium, pH and pO2 levels on neuronal function will be evaluated. Ionized calcium activity and pH will be measured in circulating arterial blood and in cerebral interstitial space with ionselective electrodes. Oxygen tension will be measured polarographically with a microelectrode. In addition, total Ca, Mg, pH, pO2, and, in some experiments, parathormone levels, will be measured in samples of arterial blood. Neuronal functions, including EEG, seizure threshold, evoked potentials, excitatory and inhibitory synaptic functions, neuronal membrane properties will be assessed in intact brain and spinal cord and in cerebral tissue slices maintained in vitro.