TY - JOUR AU - Shan, Jian AU - Kushnir, Alexander AU - Betzenhauser, Matthew J. AU - Reiken, Steven AU - Li, Jingdong AU - Lehnart, Stephan E. AU - Lindegger, Nicolas AU - Mongillo, Marco AU - Mohler, Peter J. AU - Marks, Andrew R. T1 - Phosphorylation of the ryanodine receptor mediates the cardiac fight or flight response in mice PY - 2010/12/01/ AB - During the classic “fight-or-flight” stress response, sympathetic nervous system activation leads to catecholamine release, which increases heart rate and contractility, resulting in enhanced cardiac output. Catecholamines bind to β-adrenergic receptors, causing cAMP generation and activation of PKA, which phosphorylates multiple targets in cardiac muscle, including the cardiac ryanodine receptor/calcium release channel (RyR2) required for muscle contraction. PKA phosphorylation of RyR2 enhances channel activity by sensitizing the channel to cytosolic calcium (Ca2+). Here, we found that mice harboring RyR2 channels that cannot be PKA phosphorylated (referred to herein as RyR2-S2808A+/+ mice) exhibited blunted heart rate and cardiac contractile responses to catecholamines (isoproterenol). The isoproterenol-induced enhancement of ventricular myocyte Ca2+ transients and fractional shortening (contraction) and the spontaneous beating rate of sinoatrial nodal cells were all blunted in RyR2-S2808A+/+ mice. The blunted cardiac response to catecholamines in RyR2-S2808A+/+ mice resulted in impaired exercise capacity. RyR2-S2808A+/+ mice were protected against chronic catecholaminergic-induced cardiac dysfunction. These studies identify what we believe to be new roles for PKA phosphorylation of RyR2 in both the heart rate and contractile responses to acute catecholaminergic stimulation. JF - The Journal of Clinical Investigation JA - J Clin Invest SN - 0021-9738 DO - 10.1172/JCI32726 VL - 120 IS - 12 UR - https://doi.org/10.1172/JCI32726 SP - 4388 EP - 4398 PB - The American Society for Clinical Investigation ER -