Vascular control by K+ channel trafficking

描述（由申请人提供）：小（阻力大小）脑动脉和小动脉控制局部脑血流，从而为神经元和其他脑细胞提供必要的氧气和营养。动脉收缩性的一个重要调节因子是平滑肌细胞膜电位，其由离子通道控制。高血压与包括中风和痴呆在内的脑部疾病的风险增加有关。高血压患者的脑动脉去极化，导致收缩力升高，但这种病理改变的机制尚不清楚。以前的研究主要集中在确定调节动脉平滑肌细胞质膜上离子通道活性的机制。相反，控制平滑肌细胞质膜中功能性离子通道及其辅助亚基数量的机制尚不清楚。大电导钙激活钾通道（BKCa）是动脉平滑肌细胞膜电位和收缩性的主要生理调节剂。动脉平滑肌细胞表达两种BKCa通道亚基：一种是造孔亚基（BK <$），另一种是通道生理功能所必需的辅助亚基1。该应用源于新的初步数据，表明生理刺激控制BK <$1和<$2表面表达以调节通道亚基组成、通道活性和动脉收缩性。我们还提供证据表明，高血压与调节BKCa通道亚单位表面表达的机制的病理学改变有关，从而促进血管收缩。三个具体的目标将进行调查，以测试中心的假设，即血管调节刺激调节BKCa通道亚单位的表面表达，以控制脑动脉收缩，这些过程的病理修改导致血管收缩与脑血管疾病。目的1将检验血管舒张剂和血管收缩剂调节<$1亚基表面表达以控制平滑肌细胞中BKCa通道活性和动脉收缩性的假设。目的2将研究血管收缩剂和血管舒张剂调节BK <$表面表达和降解以调节平滑肌细胞BKCa通道活性和动脉收缩性的假设。目的3将探讨高血压与刺激血管收缩的BK <$1亚基表面表达的功能失调控制有关的假说。用于测试这些假设的方法将包括动脉生物素化、FRET、RNAi、co-IP、免疫荧光、膜片钳电生理学、膜电位记录、细胞内Ca 2+成像和动脉肌电图。这一建议将提供有关脑动脉收缩调节的生理和病理机制，控制BKCa通道表面表达的重要新信息。

DESCRIPTION (provided by applicant): Small (resistance-size) cerebral arteries and arterioles control regional brain blood flow, thereby providing neurons and other brain cells with necessary oxygen and nutrients. An essential regulator of artery contractility is smooth muscle cell membrane potential, which is controlled by ion channels. Hypertension is associated with increased risk for cerebral diseases, including stroke and dementia. Cerebral arteries from hypertensive subjects are depolarized, leading to elevated contractility, but mechanisms involved in this pathological alteration are unclear. Previous studies have focused on identifying mechanisms that regulate the activity of ion channels located in the plasma membrane of arterial smooth muscle cells. In contrast, mechanisms that control the number of functional ion channels and their auxiliary subunits in the plasma membrane of smooth muscle cells are unclear. Large-conductance calcium (Ca2+)-activated potassium (BKCa) channels are a major physiological modulator of arterial smooth muscle cell membrane potential and contractility. Arterial smooth muscle cells express two BKCa channel subunits: a pore-forming ¿(BK¿) and an auxiliary ¿1 that is essential for channel physiological functions. This application stems from novel preliminary data indicating that physiological stimuli control BK¿ and ¿1 surface expression to modulate channel subunit composition, channel activity and arterial contractility. We also provide evidence that hypertension is associated with pathological alterations in mechanisms that regulate BKCa channel subunit surface expression, thereby promoting vasoconstriction. Three specific aims will be investigated to test the central hypothesis that vasoregulatory stimuli modulate surface expression of BKCa channel subunits to control cerebral artery contractility, and that pathological modification of these processes leads to vasoconstriction associated with cerebrovascular disease. Aim 1 will examine the hypothesis that vasodilators and vasoconstrictors regulate ¿1 subunit surface expression to control BKCa channel activity in smooth muscle cells and arterial contractility. Aim 2 will investigate the hypothesis that vasoconstrictors and vasodilators modulate BK¿ surface expression and degradation to regulate smooth muscle cell BKCa channel activity and arterial contractility. Aim 3 will explore the hypothesis that hypertension is associated with dysfunctional control of BK¿ and ¿1 subunit surface expression that stimulates vasoconstriction. Methods used to test these hypotheses will include arterial biotinylation, FRET, RNAi, co-IP, immunofluorescence, patch-clamp electrophysiology, membrane potential recording, intracellular Ca2+ imaging and arterial myography. This proposal will provide significant novel information concerning cerebral artery contractility regulation by physiological and pathological mechanisms that control BKCa channel surface expression.