Modulation of Voltage-gated K Channels in Glomus Cells

描述（由申请人提供）：全身性缺氧是动物潜在的致命情况。为了保护主要器官免受不可逆的损害，颈动脉体，一个主要的动脉化学感觉器官，向大脑发送信息并诱导各种系统反应。颈动脉体缺氧化学传递的机制尚不清楚，但已表明K+通道和神经递质参与其中。研究表明乙酰胆碱（acetylcholine, ACh）在球囊细胞的兴奋中起积极作用。因此，我们假设ACh和电压门控K+ (Kv)通道之间的相互作用在球囊细胞的兴奋中起重要作用。我们的初步研究表明，低剂量乙酰胆碱增强和高剂量乙酰胆碱抑制猫血管球细胞的Kv电流。我们将扩展这些研究，并研究ACh调制Kv通道的机制。膜片钳、微荧光、基因表达阵列、RT-PCR和免疫细胞化学技术将被应用。最初，我们将使用我们的猫模型，因为我们已经描述了猫血管球细胞中的Kv通道和胆碱能受体。烟碱、毒蕈碱M1和M2受体对细胞内Ca2+、PKC和酪氨酸激酶相关的Kv电流调节的贡献将被研究。这些研究将揭示ACh和Kv通道之间的相互作用如何在亚细胞水平发生（Specific Aim 1）。随后，我们将把我们的研究扩展到小鼠模型（DBA/2J和a /J菌株）。缺氧通气反应和球囊细胞对乙酰胆碱的反应在这些菌株中有很大的不同。我们假设千伏通道胆碱能调制的变化是这些差异的基础（具体目标2）。对老鼠的研究将表明这些差异是否由基因控制。本研究将对颈动脉体兴奋的机制提供新的认识。从公共卫生的角度来看，了解化学感觉和化学转导机制可能对治疗一些与颈动脉体功能相关的病理状况有价值，如原发性高血压、阻塞性睡眠呼吸暂停、prder - willi综合征异常通气、婴儿猝死综合征和先天性中枢性低通气综合征。已知这些疾病具有遗传基础。

DESCRIPTION (provided by applicant): Systemic hypoxia is a potentially lethal situation for the animal. To protect major organs from irreversible damage, the carotid body, a primary arterial chemosensory organ, sends a message to the brain and induces various systemic responses. The mechanisms of hypoxic chemotransmission in the carotid body is not still clear, but the involvement of K+ channels and neurotransmitters has been indicated. Studies have shown that acetylcholine (ACh) plays an active role in the excitation of glomus cells. Accordingly, we hypothesized that interaction between ACh and voltage-gated K+ (Kv) channels plays an important role in the excitation of glomus cells. Our preliminary studies showed that low doses of ACh enhanced and high doses of ACh inhibited Kv current in cat glomus cells. We will extend these studies and investigate mechanisms involved in the modulation of Kv channels by ACh. Patch clamp, microfluorometric, gene expression array, RT-PCR and immunocytochemical techniques will be applied. Initially we will use our cat model, because we have already characterized Kv channels and cholinergic receptors in cat glomus cells. Contribution of nicotinic, muscarinic M1 and M2 receptors to the modulation of Kv current in relation to cytosolic Ca2+, PKC and tyrosine kinase will be investigated. These studies will reveal how the interaction between ACh and Kv channels occurs at subcellular level (Specific Aim 1). Subsequently, we will extend our studies to a mouse model (DBA/2J and A/J strains). Hypoxic ventilatory responses and glomus cell responses to ACh in these strains are substantially different. We have hypothesized that variations in cholinergic modulation of Kv channels are the bases of these differences (Specific aim 2). The studies in mice will show whether these differences are genetically controlled. The proposed studies will give new insight into mechanisms of the carotid body excitation. In the perspective of public health, understanding the chemosensory and chemotransductive mechanisms may be valuable for the treatment of some pathological conditions related to carotid body function such as primary hypertension, obstructive sleep apnea, abnormal ventilation in Prader-Willi syndrome, sudden infant death syndrome and congenital central hypoventilation syndrome. These diseases are known to have a genetic basis.