Effects of K+ Accumulation/Depletion in the Heart

心脏中钾积累/消耗的影响

• 批准号: 8403979
• 负责人: Guy Salama
• 金额: $ 44.95万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-15 至 2014-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8403979
• 关键词: Adrenergic Agents; Affinity; Arrhythmia; Binding; Cardiac; Cations; Cell membrane; Cells; Cleaved cell; Coronary Vessels; Crown Ethers; Diffuse; Dyes; Ectopic beats; Electric Countershock; Electrophysiology (science); Epicardium; Equilibrium; Exhibits; Fiber; Fluorescence; Fluorescent Dyes; Fluorescent Probes; Goals; Heart; Heart Atrium; Heart Diseases; Heterogeneity; In Vitro; Intervention; Ischemia; Kinetics; Lead; Ligation; Lipid Bilayers; Liquid substance; Maps; Measures; Membrane; Membrane Potentials; Metabolic; Methods; Muscle Cells; Myocardial Ischemia; Myocardium; Optics; Pathology; Physiological; Physiology; Potassium Channel; Property; Pump; Recurrence; Regulation; Reperfusion Therapy; Reporting; Rest; Role; Tail; Testing; Time; Ventricular; adrenergic; aqueous; base; extracellular; heart electrical activity; improved; interstitial; new therapeutic target; novel strategies; premature; prevent; public health relevance; response; stop flow technique; success; uptake

DESCRIPTION (provided by applicant): Regulation of K+ in cellular and extracellular compartments is of central importance to volume regulation, fluid transport, the resting membrane potential and electrical activity in excitable cells. In heart, extracellular [K+] in narrow clefts between cells and in T-tubules is not always in diffusional equilibrium with external K+ ([K+]o ) and can be depleted or accumulated and thereby differ from [K+]o during a wide range of physiological/pathological conditions. The central goal of the project is to elucidate the consequences of extracellular K+ accumulation ([K+]a) on cardiac electrical activity in physiological and pathological conditions. To do so, we developed new K+ sensitive fluorescent probes that can be anchored to plasma membranes and upon binding to K+ produce a fluorescence change that reports the local [K+]. We can calibrate the probe, measure rapid (1 ms) changes in [K+]a in ventricular myocytes and Langendorff hearts. The Specific Aims are: Aim 1: Improve our new K+ sensitive probes consisting of: i) hydrophobic groups to anchor the probe to lipid bilayers, ii) hydrophilic groups to dissolve and prevent the probe from diffusing across the membrane into cells, iii) a fluorescent dye that senses iv) the binding of K+ to a K+- selective organic crown ether ring and exhibits a fluorescence change as a function of [K+] in the range of 1-50 mM. Aim 2: To test the hypothesis that different K+ currents contribute differently to [K+]a under different physiological conditions( ?? heartrate, ?? 2-adrenergic activity) and metabolic states. [K+]a responses will be compared during pharmacological interventions of channels responsible for K+ efflux (IK1, It,o, IK,slow, IKr, IKs, IKATP) and during manipulations of K+ re-uptake via the Na/K pumps. [K+]a will be compared in atrial and ventricular myocytes to test the effects of differences in APDs, K+ currents and T-tubules. In perfused hearts, APs and [K+]a will be simultaneously mapped, and changes in [K+]a will be measured on a beat-to-beat basis. Aim 3: To test the hypothesis that in pathological conditions, the rise of [K+]a can lead to regions of myocardium with an increase in excitability and a greater propensity to focal activity or premature beats that initiate arrhythmias. Simultaneous optical mapping of APs and [K+]a in perfused hearts will be used to measure APs and beat-to- beat changes in [K+]a transients to elucidate the role of [K+]a during arrhythmias elicited by ischemia/reperfusion applied either globally (zero flow) or locally via an LAD ligation. [K+]a elevation will be correlated with coronary vessels, fiber orientation and the origins of premature impulses. Such a project will develop K+ sensitive dyes for applications to cardiac electrophysiology and for the first time characterize [K+]a on a beat-to-beat basis. Dual optical mapping of [K+]a and APs will determine the changes in [K+]a that occur during physiological and pathological interventions, will validate methods to reduce [K+]a to offer new targets to treat cardiac diseases.

描述（由申请人提供）：对细胞和细胞外室中K+的调节对于调节体积调节，流体转运，静止膜电位和可激发细胞的电活动至关重要。在心脏中，细胞外[K+]在细胞和T管之间的狭窄裂缝中并不总是以外部K+（[K+] O）为扩散平衡，并且可以耗尽或积累，从而在广泛的生理/病理条件范围内与[K+] O不同。 该项目的核心目的是阐明细胞外K+积累（[K+] A）对生理和病理条件下心脏电活动的后果。为此，我们开发了新的K+敏感荧光探针，可以锚定在质膜上并在与K+结合后产生荧光变化，以报告局部[K+]。我们可以校准探针，测量心室心肌和兰多德夫心脏中[K+] A的快速变化（1 ms）。 The Specific Aims are: Aim 1: Improve our new K+ sensitive probes consisting of: i) hydrophobic groups to anchor the probe to lipid bilayers, ii) hydrophilic groups to dissolve and prevent the probe from diffusing across the membrane into cells, iii) a fluorescent dye that senses iv) the binding of K+ to a K+- selective organic crown ether ring and exhibits a fluorescence change as a function of [K+]在1-50毫米的范围内。 目的2：检验以下假设：在不同的生理条件下对[K+] a的不同贡献不同（heftrate，是2-肾上腺素能活性）和代谢状态。 [k+]在药理学干预过程中，将比较A反应，负责K+外排的通道（IK1，IT，O，IK，slow，slow，ikr，IKR，IKR，IKR，IKR），以及通过Na/k泵进行K+重新摄取的操作。 [K+] A将在心房和心室肌细胞中进行比较，以测试APD，K+电流和T管的差异的影响。在灌注的心脏中，APS和[K+] A将同时映射，并且[K+] A的变化将以节拍对基础进行测量。 目的3：为了检验以下假设：在病理条件下，[K+] A的兴起可以导致心肌区域，并增加兴奋性和更大的局灶性活动或过早的节拍倾向，从而引发心律不齐。 APS和[K+] A中的[K+]的[K+] A瞬变的瞬态变化将使用[K+]瞬间的触发变化，以阐明由缺血/再灌注引起的[K+] A的作用，以测量APS和[K+] A的同时光学映射。 [K+]高程将与冠状动脉血管，纤维取向和过早冲动的起源有关。 这样的项目将开发K+敏感的染料，以应用于心脏电生理学，并首次以Beat-to-Beat为基础来表征[K+] A。 [K+] A和AP的双重光学映射将确定生理和病理干预期间发生的[K+] A的变化，将验证减少[K+] A提供新目标以治疗心脏疾病的方法。

项目成果

Computational and experimental characterization of a fluorescent dye for detection of potassium ion concentration.

用于检测钾离子浓度的荧光染料的计算和实验表征。

• DOI: 10.1021/jp507552q
• 发表时间: 2014
• 期刊: The journal of physical chemistry. A
• 作者: Tanha,Matteus;Chakraborty,SubhasishK;Gabris,Beth;Waggoner,AlanS;Salama,Guy;Yaron,David
• 通讯作者: Yaron,David