Modulation of Voltage-gated K Channels in Glomus Cells

描述（由申请方提供）：全身性缺氧是动物的潜在致死情况。为了保护主要器官免受不可逆的损伤，颈动脉体，一个主要的动脉化学感受器官，向大脑发送信息并诱导各种全身反应。颈动脉体中低氧化学传递的机制尚不清楚，但已表明K+通道和神经递质的参与。研究表明，乙酰胆碱（ACh）对血管球细胞的兴奋起积极作用。因此，我们假设ACh和电压门控K+（Kv）通道之间的相互作用在血管球细胞的兴奋中起着重要作用。我们的初步研究表明，低剂量ACh可增强猫血管球细胞的Kv电流，而高剂量ACh可抑制Kv电流。我们将扩展这些研究，并探讨ACh对Kv通道的调节机制。应用膜片钳、显微荧光、基因表达芯片、RT-PCR和免疫细胞化学技术。最初，我们将使用我们的猫模型，因为我们已经在猫血管球细胞中表征了Kv通道和胆碱能受体。将研究烟碱、毒蕈碱M1和M2受体对与胞质Ca 2+、PKC和酪氨酸激酶相关的Kv电流调制的贡献。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上发生（具体目标1）。随后，我们将我们的研究扩展到小鼠模型（DBA/2J和A/J品系）。这些菌株对ACh的低血糖反应和血管球细胞反应有很大不同。我们假设Kv通道的胆碱能调节的变化是这些差异的基础（具体目的2）。对小鼠的研究将表明这些差异是否是遗传控制的。这些研究将为颈动脉体兴奋机制的研究提供新的思路。从公共卫生的角度来看，了解化学感受和化学传导机制可能对治疗原发性高血压、阻塞性睡眠呼吸暂停、Prader-Willi综合征通气异常、婴儿猝死综合征和先天性中枢性低通气综合征等颈动脉体功能相关的病理状态具有重要价值。这些疾病都有遗传基础。

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.