EDHF in the Cerebral Circulation

描述(申请人提供)：近年来，我们和其他人已经确定，除了一氧化氮和环氧合酶代谢物外，至少有一个内皮过程扩张脑血管。这一新的过程被称为内皮衍生超极化因子或EDHF，在正常生理状态和随后的病理条件下，可能是脑循环中重要的扩张器机制。在拟议的研究中，我们将探讨EDHF在脑动脉中的作用机制。有待检验的主要假说是，串联孔结构域钾通道与EDHF介导的大鼠脑血管扩张有关。为了使上述假设有效，则下列所有特定目标都必须为真。(特定目的1)串联孔结构域钾通道必须存在于脑动脉中；(特定目标2)激活串联孔结构域钾通道必须引起大脑动脉的扩张，以及(特定目标3)抑制串联孔结构域钾通道必须抑制EDHF介导的扩张。在具体目标1中，我们计划使用RT-PCR、Western分析、免疫组织化学和电生理学相结合的方法来证明脑动脉中存在串联孔结构域钾通道，并进一步证明它们具有功能。在特定的目标2中，我们将使用分离的灌流脑动脉来确定这些通道的激活是否会产生扩张。此外，我们计划确定通道表达的抑制(反义)和药物阻滞剂的抑制是否拮抗这些钾通道产生的扩张。在具体目标3中，我们建议确定抑制串联孔结构域钾通道是否抑制EDHF介导的扩张。这些研究的完成将为深入了解EDHF及其在大脑中的循环控制机制提供重要的见解。此外，我们预计有关串联孔结构域钾通道的新信息将是理解大脑循环控制的一大步。

DESCRIPTION (provided by applicant): ln recent years, we and others have determined that at least one endothelial process, in addition to NO and cyclooxygenase metabolites, dilates cerebral vessels. This new process, termed "endothelium-derived hyperpolarizing factor" or EDHF, is likely an important dilator mechanism in the cerebral circulation during normal physiological states and following pathological conditions. In the proposed studies, we will address the mechanism of EDHF in cerebral arteries. The major hypothesis to be tested is that tandem-pore domain potassium channels are involved with the EDHF-mediated dilations in cerebral vessels of the rat. In order for the above hypothesis to be valid then all of the following specific aims must be true. (Specific Aim 1) Tandem-pore domain potassium channels must be present in cerebral arteries; (Specific Aim 2) activation of tandem-pore domain potassium channels must elicit dilation in cerebral arteries, and (Specific Aim 3) inhibition of tandem-pore domain potassium channels must inhibit EDHF-mediated dilations. In Specific Aim 1, we plan to use a combination of RT-PCR, Western analysis, immunohistochemistry, and electrophysiology to demonstrate the presence of the tandem pore domain potassium channels in cerebral arteries and, further, demonstrate that they are functional. In specific Aim 2, we will use isolated perfused cerebral arteries to determine if activation of these channels produces dilation. Furthermore, we plan to determine if inhibition of channel expression (anti-sense) and inhibition by pharmacological blockers antagonizes dilations produced by these potassium channels. In Specific Aim 3, we propose to determine if inhibition of tandem pore domain potassium channels inhibit EDHF-mediated dilations. Completion of the proposed studies will provide important insight into EDHF and its mechanism of circulatory control in brain. Furthermore, we anticipate that new information regarding tandem pore domain potassium channels will be a big step in the understanding of cerebral circulatory control.