Autoregulation of Cerebral Blood Flow

描述（由申请人提供）：关于脑血流（CBF）自动调节的压力诱导的肌源性调节的细胞和离子机制，存在大量的文献。然而，我们对压力激活动脉壁肌张力的机制了解甚少。我们在此应用中描述了一个动物模型，其中一种大鼠，小鹿兜帽鼠（FHH）在面对动脉压升高时不能自动调节CBF，然而，经过多年的9代经济杂交，我们发现棕色挪威（BN）大鼠1号染色体上一个区域的转移在FHH. 10亿经济大鼠中恢复了肌源性表型。很明显，1号染色体上的一个位点包含一个基因编码，用于触发肌原性张力，以响应动脉压的变化。3-5年的对1号染色体的选择性操作和杂交后代F1代的表型分析已经将这条染色体的区域缩小到包含内收蛋白3 （Add3）和DUSP-5基因以及其他不完整基因的1.2 M碱基对数量性状位点（QTL）。这个1.2 M碱基QTL的转移在FHH大鼠中赋予了正常的自动调节表型。在初步实验中，我们使用siRNA方法敲除Add3和DUSP-5蛋白，通过敲除Add3和DUSP-5蛋白水平，显著降低了自动调节能力。本应用程序中描述的协议旨在定义在这个1.2 M碱基QTL中负责Add3， DUSP-5或其他尚未确定的基因作用的细胞信号级联。同样，我们将确定负责压力诱导的膜去极化的离子种类，这是启动和维持压力诱导的肌张力所必需的。这些大鼠品系是同源动物模型，允许鉴定负责压力诱导的自我调节的机制，其中背景基因型不会发生代偿性变化，不像在敲除小鼠中可能发生的变化。

DESCRIPTION (provided by applicant): There exists a substantial amount of literature regarding the cellular and ionic mechanisms responsible for pressure-induced myogenic regulation of cerebral blood flow (CBF) autoregulation. However, our understanding of the mechanisms by which pressure activates myogenic tone in the arterial wall is only poorly understood. We describe in this application an animal model in which one rat strain, the Fawn Hooded rat (FHH) does not auto regulate CBF in the face of an increasing arterial pressure, whereas, years of consomic interbreeding of 9 generation breeding we found that transfer of a region on chromosome 1 of a Brown Norway (BN) rat recovered the myogenic phenotype in the FHH.1BN consomic rat. It became clear that a locus on chromosome 1 contained a gene coding for the trigger of myogenic tone in response to changes in arterial pressure. 3-5 years of selective manipulation of chromosome 1 and phenotyping F1 generations of interbred offspring have narrowed the region of this chromosome to a 1.2 M base pair quantitative trait loci (QTL) containing the gene for adducin3 (Add3) and DUSP-5 along with other incomplete genes. Transfer of this 1.2 M base QTL confers a normal auto regulatory phenotype in the FHH rat. Using siRNA methodology to knockdown Add3 and DUSP-5 we have, in preliminary experiments, significantly reduced auto regulatory capacity by knocking down Add3 and DUSP-5 protein levels. Protocols described in this application are designed to define the cellular signaling cascades responsible for the actions of Add3, DUSP-5 or other yet unidentified genes in this 1.2 M base QTL. Similarly, we will identify the ionic species responsible for pressure-induced membrane depolarization which is necessary for initiation and maintenance of pressure-induced myogenic tone. These rat strains are the congenic animal model allowing identification of the mechanisms responsible for pressure-induced autoregulation in which no compensatory changes in the background genotype can occur, unlike that which can occur in a knockout mouse.