Assessment of cardiomyocyte size

Myocytes make up about 75% of ventricular mass but are outnumbered by nonmyocardial cells. Chamber dilatation in progression to heart failure is largely due to myocyte lengthening from series addition of new sarcomeres, while increased cross-sectional area accounts for changes in wall thickness. Coronary perfusion with collagenase can be used to obtain isolated myocytes for determination of myocyte dimensions. It consists of the following steps: (1) heart removal and aortic cannulation; (2) coronary perfusion with media followed by collagenase; (3) myocyte dissociation; (4) myocyte fixation; (5) determination of cell volume (V) by Coulter Channelyzer, length (L) microscopically, and cross-sectional area from V/L. Not only does this approach provide precise, comprehensive, and reproducible results, it allows direct comparisons between all published data collected in this manner.