CLOCK and myocardial infarction: In a rat myocardial infarction model, norepinephrine and isoprenaline show circadian rhythms in cardiomyocytes, and the CLOCK/BMAL1 dimer binds to the enhancer of the β1-adrenoceptor gene to upregulate its expression, thereby regulating the circadian rhythm of ventricular arrhythmias in rats with chronic heart failure.