Effect of distinct sources of Ca2+ on cardiac hypertrophy in cardiomyocytes

It is believed that intracellular calcium (Ca2+) overload can cause the cardiac hypertrophy, but it is possible that the Ca2+ entering the cytoplasm through distinct pathways will induce various effects on cardiomyocytes. The aim of the present study is to explore the effect of different sources of Ca2+ on cardiomyocyte hypertrophy. The cardiomyocytes isolated from neonatal Sprague–Dawley rats were treated with three agents (ionomycin, caffeine and angiotensin II [Ang II]) that increased the intracellular Ca2+ concentration via different pathways. Treatments with ionomycin, caffeine and Ang II for 24 h caused a significant increase in resting [Ca2+]i by 108.0 ± 7.8%, 102.0 ± 6.9% and 59.8 ± 3.3%, respectively. Caffeine and Ang II increased the cell surface area of cardiomyocytes and the mRNA level of atrial natriuretic peptide, brain natriuretic peptide and β-myosin heavy chain, but ionomycin did not. Moreover, sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) activity and the amplitudes of the twitch [Ca2+]i ...