Functional Analysis of Carotid Body Responses to Hypoxia in Mice"

描述（由申请人提供）：颈动脉体在感知缺氧中的作用已经得到了很好的证实。它还涉及一些人类健康疾病，如小岛屿发展中国家，睡眠呼吸暂停，先天性中枢性低通气综合征，慢性心力衰竭和原发性高血压。此外，这些疾病与遗传易感性密切相关。为了研究遗传相关疾病，近交或基因操纵的小鼠模型是一种理想的研究工具。为了应对缺氧，颈动脉体通过增加颈动脉化学感受器传入神经输出来激活呼吸中枢。因此，研究颈动脉整体功能最直接的方法是测量颈动脉窦神经传入活动。这些研究大多是在大型动物身上进行的。虽然有几项研究记录了小鼠颈动脉窦神经的体外活动，但其特征仍未得到很好的描述。不用说，为了将遗传与颈动脉功能改变和人类健康障碍直接联系起来，需要使用近亲繁殖或基因操纵的小鼠进行体内研究。我研究的长期目标是研究遗传学在调节颈动脉身体功能和颈动脉身体相关的人类健康疾病中的作用。对于这个应用，我将把颈动脉身体功能的体内评估和一个分子靶点BK通道连接起来。BK通道存在于颈动脉体的化学感应血管球细胞中，并受到缺氧的抑制。这种氧感应元件的下游是血管球细胞内钙的增加，随后是神经递质释放和颈动脉窦神经活动的变化。目的1是建立小鼠体内模型，研究CB对缺氧的反应。我将在C57BL/6J小鼠菌株中建立体内CSN记录，这是许多转基因小鼠的背景菌株。在目的2中，我将探讨BK通道在体内颈动脉机体对缺氧的整体反应中所起的作用。我将使用功能性BK通道表达较高的DBA/2J品系、BK通道表达较低的A/J品系和BK通道敲除小鼠（BK- ko）来研究BK通道在颈动脉机体缺氧反应中的作用。这两个目标将使我们能够描述BK通道在功能范围内发挥的作用。为了将这项工作与化学受体细胞功能联系起来，我将尝试将AIM 2的体内反应与血管球细胞功能的体外测量联系起来。体外研究颈动脉体功能的主流方法之一是测量血管球细胞内钙的变化。因此，我研究的最后一个目的将是探索小鼠颈动脉体中BK通道组成、CSN活性和血管球细胞内钙变化之间的关系（aim 3）。

DESCRIPTION (provided by applicant): The carotid body's role in sensing hypoxia is well established. It has also been implicated in several human health disorders such as SIDS, Sleep Apnea, Congenital Central Hypoventilation Syndrome, chronic heart failure and primary hypertension. Furthermore, these disorders have been strongly linked to a genetic predisposition. In order to study genetically linked disorders, an inbred or genetically manipulated mouse model is an ideal tool for investigation. In response to hypoxia, the carotid body activates respiratory centers via increasing the carotid chemoreceptor afferent nerve output. Thus, the most direct method for studying the overall carotid body's function is measuring the afferent carotid sinus nerve activity. Such studies have been done mostly in large animals. Although several studies have recorded mouse carotid sinus nerve activity in vitro, its characteristics are still not well described. Needless to say, studies in vivo using inbred or genetically manipulated mice are required in order to directly link genetics with altered carotid body function and human health disorders. The long term objective of my research is to study the role that genetics play in modulating carotid body function and carotid body-related human health disorders. For this application, I shall bridge in vivo assessment of the carotid body function and one molecular target, BK channels. BK channels are present in chemosensing glomus cells of the carotid body and are inhibited by hypoxia. Downstream from this oxygen sensing element is an increase in intracellular calcium in glomus cells followed by neurotransmitter release and a subsequent change in carotid sinus nerve activity. AIM 1 is to develop an in vivo murine model to study CB responses to hypoxia. I will establish in vivo CSN recordings in C57BL/6J mouse strain that is the background strain in many genetically altered mice. In aim 2,1 will explore the role that BK channels play in the overall in vivo carotid body responses to hypoxia. I will use the DBA/2J strain with its higher expression of functional BK channels, the A/J strain with lower expression of BK channels, and BK channel knockout mice (BK-KO) to study the role that BK channels play within the carotid body in response to hypoxia. These two aims will allow us to characterize the role that BK channels play within a functional scope. In order to link this work to chemoreceptor cell function, I will try to link AIM 2's in vivo responses to in vitro measures of glomus cell function. One of the main-stream methods of studying carotid body function in vitro is by measuring changes in glomus cell intracellular calcium. Accordingly, the last aim of my research will be to explore the association between BK channels composition, CSN activity and changes in glomus cell intracellular calcium in the mouse carotid body (AIM 3).