Chemically inducing ageing in neonatal rat ventricular myocytes

Cardiovascular diseases are the leading cause of deaths worldwide. Age is an important risk factor. Cardiovascular ageing is characterised by a decline in cardiac function attributed to changes in ultrastructure and calcium homeostasis. Typically, cellular ageing is studied longitudinally, by comparing young and old animals. These studies are effective, but expensive and time consuming. Recent work has shown that neuronal ageing can be acutely studied following incubation with hydroxyurea (HU) or D-galactose. To date, this chemically-induced ageing model has not been extended to cardiomyocytes. In this study, we induced ageing of neonatal rat ventricular myocytes (NRVM) using HU (cells were incubated with 50 or 500 µM HU for up to 7 days). Using calcium imaging, we showed that HU treatment decreased the ability of cardiomyocytes to follow electrical pacing and increased the generation of alternans; known pro-arrhythmic behaviours. EM analysis revealed that HU treatment increased the appearance of autophagosomes, rough sarcoplasmic reticulum and gangliosides. Our results indicate that prolonged incubation with HU evoked changes in the ultrastructure and calcium homeostasis of cardiomyocytes similar to those observed in naturally aged cells. We propose that chemically induced ageing provides a relevant model of cellular ageing, which can be applied acutely and inexpensively