Mechanisms of Coronary Vasomotor Control

描述（由申请人提供）：本提案的总体目标是阐明传导代谢信号的血管效应器，这些代谢信号使血流与心脏代谢-代谢扩张联系起来。心脏依靠代谢扩张来产生有氧能量，因为无氧储备几乎不存在；然而，负责耦合血流到心脏代谢的效应器仍未确定。血流与代谢的匹配是重要的，可能在心脏微血管疾病中起作用。我们认为Kv通道将H2O2代谢信号转化为氧化还原介导的冠状动脉代谢血管舒张。由于Kv1通道家族的某些成员是氧化还原敏感的（例如，Kv1.2, 1.3和1.5），我们的第一个目标是确定哪些氧化还原感应Kv通道将代谢信号传导到心脏中。这一目标将使用函数的损失和增益方法进行测试。功能丧失将使用小鼠对Kv1.5和1.3通道的零值，对Kv1.2通道的杂合零值（Kv1.2-/-是致命的），功能获得将使用平滑肌特异性Tet On系统驱动Kv通道的表达来研究特定离子通道的表达。我们发现糖尿病db/db小鼠的代谢扩张受损，这些小鼠动脉中Kv1.2、1.3和1.5通道的表达显著降低。在第二个目标中，我们的目标是通过在平滑肌中使用Tet诱导系统表达Kv1.5、1.2和/或Kv1.3通道，在db/db小鼠中进行功能增益研究。我们的总体策略是测量心脏工作，心肌血流量和组织氧合之间的关系，以及评估心功能和心肌缺血的措施。我们还将进行体外研究，以确定心肌细胞血管活性代谢物的产生，分离小动脉的血管反应性和平滑肌的电生理参数。这种从电生理学到体内血流调节的综合方法应该能够解答基本的冠状动脉生理学和血流调节，以及糖尿病心肌病的潜在治疗方法。

DESCRIPTION (provided by applicant): The overarching aim of this proposal is to elucidate vascular effectors that transduce metabolic signals that enable the connection of flow to cardiac metabolism-metabolic dilation. The heart is dependent on metabolic dilation for aerobic energy production because anaerobic reserve is virtually non-existent; however, the effectors responsible for coupling flow to metabolism in the heart remain unidentified. The matching of flow to metabolism is important and may play a role in microvascular diseases in the heart. We have suggested that Kv channels transduce the H2O2 metabolic signal into redox- mediated coronary metabolic vasodilation. Because certain members of the Kv1 family of channels are redox sensitive (e.g., Kv1.2, 1.3 and 1.5), our first goal will determine, which redox sensing Kv channels transduce metabolic signals to flow in the heart. This aim will be tested using loss and gain of function approaches. Loss of function will use mice null for Kv1.5 and 1.3 channels, and heterozygous null for Kv1.2 channels (Kv1.2-/- is lethal), and gain of function will study of expression of the specific ion channel using a smooth muscle specific Tet On system driving expression of the Kv channel. We have found that metabolic dilation in the diabetic db/db mouse is impaired and that expression of Kv1.2, 1.3, and 1.5 channels is substantially decreased in arteries of these mice. Our goal in the second aim is to perform gain of function studies in db/db mice by expressing Kv1.5, 1.2 and/or Kv1.3 channels using the Tet inducible system in smooth muscle. Our overall strategy is to measure the relationship between cardiac work, and myocardial blood flow and tissue oxygenation along with evaluating measures of cardiac function and myocardial ischemia. We also will perform in vitro studies to determine the production of vasoactive metabolites from cardiac myocytes, vascular reactivity of isolated arterioles and electrophysiological parameters in smooth muscle. This integrated approach-from electrophysiology to in vivo flow regulation should enable answers regarding basic coronary physiology and flow regulation, as well as potential therapies for diabetic cardiomyopathy.