Evaluating the Mechanical Properties of Isolated Rat Cardiomyocytes Sarcolemma Using Atomic Force Microscopy

Incidence of cardiac diseases, one of the leading causes of death worldwide, is still on the rise. As the cardiomyocyte is the contractile unit of the heart, knowledge on the details of its mechanical structure and functionality is helpful to the understanding of myocardial pathophysiology and development of therapeutic approaches. Atomic force microscopy (AFM) has been used not only for topographic surface imaging but also for direct assessment of the mechanical characteristics of the plasma membrane. In this work, a preliminary study was conducted focusing on factors affecting the elasticity (E) of the sarcolemma (SL) of isolated rat ventricular myocytes, which was determined using AFM. After collecting the topographic image, 16 × 16 force map was generated and post-analyzed using the Hertz model to estimate the Young’s modulus (i.e., E). The investigated factors influencing on E were position (32), cell (18), heart (12), and post-isolation storage period. Appreciable variability was observed for all factors, apparently due to differences in maximum forces, speeds and depths of indentation which could have a great influence on E. Also, longer storage was associated with decreased E values (< 10 h: 10.96 ± 0.08kPa; n = 5902; > 12h; 6.48 ± 0.05kPa; n = 2012), probably due to cell deterioration with time. Accurate measurement of E is essential to detect alterations in cell function and effect of therapeutic drugs due to changes in SL mechanical properties. From the present results, it is possible to conclude that storage must be as short as possible, and that other alternatives should be sought for verifying cell viability and improving cell attachment.