Imagings of Sarcomeres in Rat Neonatal Cardiomyocytes Expressing Stress Fiber-Like Structures

Abstract

In the present study, we investigated whether sarcomeric dynamics is influenced by the development of stress fiber-like structures, and observed sarcomeres of rat neonatal cardiomyocytes by time-lapse imaging. Ventricular myocytes were isolated from 1-day-old Wistar rats, and cultured on collagen-coated glass bottom dishes. We observed a decrease in the number of sarcomeres 100 hrs) and development of stress fiber-like structures likely to be formed via degradation of sarcomeric≥upon long-term culture (proteins. Sarcomere length (SL) nanometry (Shintani et al. J Gen Physiol. 2014; Shintani et al., BBRC 2015) was performed at 37±0.5°C. The formation of stress fiber-like structures did not significantly alter the lengths of remaining sarcomeres at rest, and shortening velocity was increased while lengthening velocity was decreased in single sarcomeres, coupled presumably with a change in the tug-of-war between sarcomeres in myofibrils. We hereby conclude that in neonatal cardiomyocytes, 1) intracellular stress fiber-like structures develop, and 2) the formation of stress fiber-like structures did not significantly alter the average lengths of remaining sarcomeres at rest, 3) the contractility of remained sarcomeres is maintained.