Motohisa Osaka

Learn More
Recently, we developed a transgenic mouse with cardiac-specific Gsalpha overexpression (TG mouse), which exhibits enhanced postsynaptic beta-adrenergic receptor signaling, ultimately developing a cardiomyopathy. The goal of the present study was to determine whether cardiac Gsalpha overexpression alters autonomic cardiovascular control, which could shed(More)
The important role of alpha 1-adrenoceptors in reperfusion ventricular arrhythmia is mentioned in the introduction. However, the present report is concerned with the sinus node. It is speculated that the decreased positive chronotropic action of alpha 1-adrenergic stimulation due to aging may contribute to the development of sick sinus syndrome.
T-wave alternans and QT dispersion were compared as predictors of the outcome of electrophysiologic study and arrhythmia-free survival in patients undergoing electrophysiologic evaluation. T-wave alternans was a highly significant predictor of these 2 outcome variables, whereas QT dispersion was not.
BACKGROUND Approximately 5% of motor vehicle deaths are assumed to be occur because of a cardiac event thought to be triggered by multiple factors. One important factor is an imbalance of sympathetic and parasympathetic nervous activities, which can be measured by analyzing heart rate variability (HRV). Therefore, a system has been developed to make(More)
A mutual information (MI) method for assessment of the relationship between hemodynamic variables was proposed and applied to the analysis of heart rate (HR), arterial blood pressure (BP), and renal sympathetic nerve activity (RSNA) in artificial heart-implanted dogs to quantify correlation between these parameters. MI measures the nonlinear as well as(More)
BACKGROUND The triggering role of the autonomic nervous system in the initiation of ventricular tachycardia has not been established. To investigate the relationship between changes in autonomic activity and the occurrence of nonsustained ventricular tachycardia (NSVT) we examined heart rate variability (HRV) during the 2-hour period preceding spontaneous(More)
The nonlinearity of cardiovascular regulation is higher in normal physiology, whereas several diseases are characterized by a reduction in this nonlinearity. Reduced nonlinearity of heart rate regulation is a robust risk factor for high mortality in patients with myocardial infarction. We investigated the changes in linear and nonlinear correlations of(More)
Accentuated sympathetic nerve activity (SNA) is a risk factor for cardiovascular events. In this review, we investigate our working hypothesis that potentiated activity of neurons in the rostral ventrolateral medulla (RVLM) is the primary cause of experimental and essential hypertension. Over the past decade, we have examined how RVLM neurons regulate(More)
AIMS The level of circulating soluble elastin (CSE) is reported to increase proportionally with the degree of clinical atherosclerosis; however, its diagnostic use is limited because CSE also increases with age. We aimed to investigate whether alterations in CSE concentrations are implicated in potential cardiovascular dysfunctions (indicated by standard(More)