The release of Ca from the sarcoplasmic reticulum in heart is activated by Ca. This has the potential to be an inherently self-regenerating process, yet it is well controlled and graded relative to the level of activating Ca. It has been proposed by the investigator that single RyR channel adaptation may serve as a negative feedback mechanism that counters or stabilizes the intrinsic positive feedback of the Ca-induced Ca release mechanism. This project will utilize single channel approaches to address two Aims. The first will test the hypothesis that adaptation of single RyR channels does serve to stabilize the CICR process in heart. Rapid changes in free Ca generated by laser flash photolysis of caged compounds will be utilized to define the activation and deactivation kinetics of cardiac RyR channels reconstituted into planar bilayers. These data will be used to differentiate deactivation from slower regulatory mechanisms, such as adaptation and/or inactivation. The properties of these slower mechanisms will be analyzed and used to test several existing models of RyR adaptation.
The second Aim will test the hypothesis that brief trigger Ca signals less than 1 msec in duration are adequate to activate the RyR channel and that activation of a single RyR channel is sufficient to produce a Ca spark. Photolysis of caged Ca will be used to generate brief trigger Ca stimuli in the vicinity of single cardiac RyR channels reconstituted in bilayers to define the kinetic limits of an effective trigger Ca signal. To define the basis of the Ca spark, Ca translocation through RyR channels in bilayers will be imaged using a confocal microscope. How single RyR channel gating governs the spatial and temporal features of the spark will be defined. Based on these data, a model that deconvolves Ca spark-like fluorescence signals and accurately predicts the underlying channel gating behavior will be developed and tested in cells. In a final series of studies, the investigator will attempt to define the properties of an effective trigger Ca signal.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Physiology Study Section (PHY)
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Lymn, Richard W
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Loyola University Chicago
Schools of Medicine
United States
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Zsolnay, Vilmos; Fill, Michael; Gillespie, Dirk (2018) Sarcoplasmic Reticulum Ca2+ Release Uses a Cascading Network of Intra-SR and Channel Countercurrents. Biophys J 114:462-473
Yan, Jiajie; Thomson, Justin K; Zhao, Weiwei et al. (2018) Role of Stress Kinase JNK in Binge Alcohol-Evoked Atrial Arrhythmia. J Am Coll Cardiol 71:1459-1470
Yan, Jiajie; Zhao, Weiwei; Thomson, Justin K et al. (2018) Stress Signaling JNK2 Crosstalk With CaMKII Underlies Enhanced Atrial Arrhythmogenesis. Circ Res 122:821-835
Berti, Claudio; Zsolnay, Vilmos; Shannon, Thomas R et al. (2017) Sarcoplasmic reticulum Ca2+, Mg2+, K+, and Cl- concentrations adjust quickly as heart rate changes. J Mol Cell Cardiol 103:31-39
Uehara, Akira; Murayama, Takashi; Yasukochi, Midori et al. (2017) Extensive Ca2+ leak through K4750Q cardiac ryanodine receptors caused by cytosolic and luminal Ca2+ hypersensitivity. J Gen Physiol 149:199-218
Kanaporis, Giedrius; Blatter, Lothar A (2017) Membrane potential determines calcium alternans through modulation of SR Ca2+ load and L-type Ca2+ current. J Mol Cell Cardiol 105:49-58
S√łndergaard, Mads Toft; Liu, Yingjie; Larsen, Kamilla Taunsig et al. (2017) The Arrhythmogenic Calmodulin p.Phe142Leu Mutation Impairs C-domain Ca2+ Binding but Not Calmodulin-dependent Inhibition of the Cardiac Ryanodine Receptor. J Biol Chem 292:1385-1395
Kanaporis, Giedrius; Blatter, Lothar A (2017) Alternans in atria: Mechanisms and clinical relevance. Medicina (Kaunas) 53:139-149
Ramos-Franco, Josefina; Fill, Michael (2016) Approaching ryanodine receptor therapeutics from the calcin angle. J Gen Physiol 147:369-73
Zhang, Jingqun; Zhou, Qiang; Smith, Chris D et al. (2015) Non-?-blocking R-carvedilol enantiomer suppresses Ca2+ waves and stress-induced ventricular tachyarrhythmia without lowering heart rate or blood pressure. Biochem J 470:233-42

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