Modulation of Voltage-gated K Channels in Glomus Cells

描述(申请人提供)：全身性缺氧对动物来说是一种潜在的致命情况。为了保护主要器官免受不可逆转的损害，颈动脉小体作为主要的动脉化学感觉器官，向大脑发送信息并引发各种全身反应。低氧化学传递在颈动脉小体的机制尚不清楚，但已有研究表明K+通道和神经递质参与其中。研究表明，乙酰胆碱(ACh)在球体细胞的兴奋中起着积极的作用。因此，我们推测ACh和电压门控K+(Kv)通道之间的相互作用在球体细胞的兴奋中起着重要作用。我们的初步研究表明，低剂量的ACh增强猫球体细胞的Kv电流，而高剂量的ACh则抑制Kv电流。我们将扩展这些研究，并探讨ACh调节Kv通道的机制。将应用膜片钳、显微荧光、基因表达阵列、RT-PCR和免疫细胞化学技术。首先，我们将使用我们的CAT模型，因为我们已经确定了猫球瘤细胞中的Kv通道和胆碱能受体。烟碱型、毒鼠型M1和M2受体在Kv电流与胞内钙离子、蛋白激酶C和酪氨酸激酶的调节中的作用将被研究。这些研究将揭示ACh和Kv通道之间的相互作用是如何在亚细胞水平上发生的(特定目标1)。随后，我们将把我们的研究扩展到小鼠模型(DBA/2J和A/J株)。这些菌株的低氧呼吸反应和血管球体细胞对ACh的反应本质上是不同的。我们假设Kv通道胆碱能调节的变化是这些差异的基础(特定目标2)。在老鼠身上进行的研究将表明这些差异是否受基因控制。提出的研究将为颈动脉小体兴奋的机制提供新的见解。从公共卫生的角度了解其化学感觉和化学转导机制，可能对治疗与颈动脉机体功能有关的一些病理疾病，如原发性高血压、阻塞性睡眠呼吸暂停、Prader-Willi综合征中的换气异常、婴儿猝死综合征和先天性中枢性低通气综合征等具有重要意义。众所周知，这些疾病有遗传基础。

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.