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Aim To investigate the inotropic effect of PF-04957325, a phosphodiesterase type 8 inhibitor, in normal rats and its underlying molecular mechanism. Methods The techniques of in vivo rat left ventricular pressure-volume loop (P-V loop) and isolated perfusion rat heart were used to analyze the hemodynamics and positive inotropic effect of rat hearts. The Ca transient induced by field stimulation was used to analyze the hemodynamics of sarcoplasmic reticulum (SR) Ca + uptaking. Western blot was used to analyze the phosphorylation levels of SR phospolamban (PLB) and ryanodine receptor type 2 (RyR2). Results The P-V loop experiment indicated that PF-04957325 (0.5 mg · kg
ABSTRACT
Cardiomyopathy is a heterogeneous heart disease characterized by abnormalities in myocardial structure and function, which ultimately leads to heart failure even death. RNA-binding motif protein 20 (RBM 20) is a family of serine/arginine-rich proteins, highly expressed in heart. It plays an important role in the assembly and alternative splicing of RNA spliceosome, and participates in the development of cardiomyopathy. RBM 20 regulates the alternative splicing of Titin, RyR 2, LDB 3, CaMKIIô, CACNA1C involved in diastolic function, sarcomere assembly and ion transport. In this review, the role of RBM 20 in cardiomyopathy and the regulatory mechanisms of RBM 20 is summarized.
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Objective@#To explore the clinical and molecular genetic features of a Chinese patient with catecholaminergic polymorphic ventricular tachycardia (CPVT).@*Methods@#Clinical data including resting electrocardiography, echocardiography and treadmill exercise testing of a patient with CPVT admitted to our department in March 2013 were analyzed, and the peripheral venous blood samples of the patient and his family members and 400 ethnicity-matched healthy controls were obtained. All exons and exon-intron boundaries of the six CPVT-related genes including RYR2, CASQ2, TRDN, CALM1, KCNJ2 and ANKB were sequenced to detect the variants related to CPVT. The relationship between the genotypes and phenotypes was analyzed to direct the target therapy.@*Results@#Recurrent syncope induced either by exercise or extreme frightened fear was observed in this patient. There was no positive family history of syncope or sudden death. The resting electrocardiography and echocardiography of the patient were normal, while the exercise testing revealed bidirectional and polymorphic ventricular tachycardia. A cardiac ryanodine receptor gene mutation (R2401H) was identified in this patient, while this mutation was absent in his parents and sister and 400 controls. No variant was detected in the remaining five candidate genes. Treatment with high dose of metoprolol succinate (118.75 mg/d) was effective and patient was free of syncopal attack during the 2 years follow-up.@*Conclusion@#This is the first report on RyR2-R2401H mutation in Chinese patient with CPVT, and high dose of metoptolol is the effective therapy option for CPVT related to RyR2 mutation.