Functional Analysis of Carotid Body Responses to Hypoxia in Mice"

描述(由申请人提供)：颈动脉小体在感知缺氧方面的作用已经确立。它还与几种人类健康疾病有关，如小儿麻痹症、睡眠呼吸暂停、先天性中枢低通气综合征、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有很强的联系。为了研究遗传相关疾病，近亲繁殖或基因操纵的小鼠模型是一种理想的研究工具。作为对低氧的反应，颈动脉小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，研究整个颈动脉体部功能最直接的方法就是测量颈动脉窦传入神经的活动。这类研究大多是在大型动物身上进行的。虽然已有几项研究记录了小鼠颈动脉窦神经在体外的活动，但其特征仍未得到很好的描述。不用说，需要使用近亲繁殖或基因操作的小鼠进行体内研究，以便直接将遗传学与颈动脉身体功能改变和人类健康疾病联系起来。我这项研究的长期目标是研究遗传学在调节颈动脉体部功能和与颈动脉体部相关的人类健康疾病中所起的作用。对于这一应用，我将在体内评估颈动脉体功能和一个分子靶点BK通道之间架起桥梁。BK通道存在于颈动脉小体的化学感受性球体细胞中，并被低氧抑制。在这个氧感应元件的下游是球体细胞内钙的增加，随后是神经递质的释放，随后是颈动脉窦神经活动的变化。目的1建立小鼠在体模型，研究脐带血对缺氧的反应。我将在体内建立C57BL/6J小鼠品系的CSN记录，这是许多基因改变小鼠的背景品系。在目标2中，1将探讨BK通道在体内整体颈动脉体对低氧反应中所起的作用。我将使用功能性BK通道高表达的DBA/2J品系、BK通道低表达的A/J品系和BK通道基因敲除小鼠(BK-KO)来研究BK通道在颈动脉体内对低氧反应的作用。这两个目标将使我们能够描述BK渠道在功能范围内所扮演的角色。为了将这项工作与化学感受器细胞功能联系起来，我将尝试将AIM 2‘S在体内的反应与体外测定的球体细胞功能联系起来。在体外研究颈动脉体部功能的主流方法之一是通过测量球体细胞内钙离子的变化。因此，我的研究的最后目的将是探索BK通道组成、CSN活性与小鼠颈动脉体球细胞内钙变化之间的关系(AIM3)。

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).