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Influence of calcium on proliferation and phenotype alteration of cardiomyocyte in vitro
Author(s) -
Harayama Hiroaki,
Koide Masafumi,
Obata Koji,
Iio Akio,
Iida Masato,
Matsuda Nahomi,
Akins Robert E.,
Yokota Mitsuhiro,
Tuan Rocky S.,
Saito Hidehiko
Publication year - 1998
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/(sici)1097-4652(199811)177:2<289::aid-jcp11>3.0.co;2-5
Subject(s) - thapsigargin , lactate dehydrogenase , tropomyosin , calcium , cell growth , biology , serca , myocyte , microbiology and biotechnology , endoplasmic reticulum , cell cycle , creatine kinase , cell , myosin , medicine , endocrinology , atpase , biochemistry , enzyme
An accelerated weight gain is noted in the heart of Ca‐deficient, hypertensive chick embryos maintained in a shell‐less culture in vitro. We previously observed that the Ca handling property of cardiomyocytes isolated from the shell‐less embryo is altered, i.e., faster Ca uptake, suggesting a requirement for adequate Ca supply and/or proper Ca handling in embryonic cardiac development. In this study, we have examined the function of Ca on cardiomyocytes by analyzing the effects of (1) various Ca concentration in the culture medium (NCa, 1.8 mmol/L; HCa, 2.8 mmol/L; LCa, 0.9 mmol/L), and (2) various modulators of Ca handling on cell proliferation and phenotype regulation in chick embryonic cardiomyocytes. The analytical parameters included cell number, DNA content, expression of cell cycle–specific and cardiomyocyte‐specific proteins, and creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) enzyme activities. Cell number and total DNA were significantly larger ( P < 0.01) in LCa cultures compared with those in NCa. The level of LDH was elevated ( P < 0.01), but that of CPK was lowered in LCa. Expression of the G1‐S–specific protein PCNA was raised, but that of the contractile proteins myosin and tropomyosin was substantially suppressed in LCa; in HCa, the cells did not proliferate as well, whereas the level of contractile proteins was higher. Thapsigargin, a sarcoplasmic reticulum (SR)‐specific, Ca‐ATPase inhibitor, simulated the effects of LCa by enhancing cell proliferation and lowering the expression of tropomyosin. These results suggest that culturing in low Ca concentration and inhibition of SR Ca pumping enhance myocardial cell proliferation and suppress sarcomeric protein expression, perhaps by inducing cellular de‐differentiation. The in vitro effects of medium Ca concentration and Ca handling modulators on cardiomyocytes also suggest that the in vivo cardiomegaly of the SL embryos is a direct result of Ca‐deficiency, and that Ca is important in the phenotype regulation of cardiomyocytes. J. Cell. Physiol. 177:289–298, 1998. © 1998 Wiley‐Liss, Inc.