Performing a single heart beat depends on the detailed composition of the many millions of muscle cells (cardiomyocytes) that make up this vital organ. This microscopic ensemble of rat cardiomyocytes, magnified over 500 times, shows how proteins within the cells align (green- and red-stained stripes) to form myofibrils - the beating structures of the heart. Myofibrils within each cell (nuclei shown in blue) contract and relax in synchrony with others in adjacent cells, and together orchestrate the heart’s rhythmic beat. And even when the cells are removed from the heart and placed in a lab culture dish the beat goes on, helping scientists understand how myofibrils are composed as the heart develops. Identifying exactly what makes a heart beat will help researchers uncover the causes of life-threatening heart conditions such as cardiomyopathy.
Written by Caroline Cross
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