Longevity of adult ventricular rat heart muscle cells in serum-free primary culture.

The study had two aims: first, to improve the longevity of isolated adult cardiomyocytes in serum-free culture, and, second, to investigate whether catecholamines which promote hypertrophy in vivo can prolong survival of isolated adult rat cardiomyocytes in serum-free culture. The basic cell culture medium consists of serum-free medium 199 with 10(-7) M insulin. In this medium 50% of the initially plated cardiomyocytes survive in elongated form for 2 days. Omission of glutamine and supplementation of the basic medium with 5 mM creatine, 2 mM carnitine and 5 mM taurine extends survival of elongated cells to 14 days. In supplemented medium, normal cell ATP content is maintained (27 nmol/mg protein after 15 days), but cells gradually atrophy and reduce their protein mass. The trophic effects of catecholamines (epinephrine, norepinephrine, phenylephrine; 10 microM, added on day 3 of culture) were investigated. After addition of catecholamines the cells spread. Spreading can be prevented by prazosin (10 microM) and phentolamine (10 microM) but not by propranolol (10 microM), indicating that spreading is stimulated via the alpha 1-adrenoreceptor. Cells also spread in the presence of the phorbol ester phorbol myristate acetate (10 microM). Catecholamines reduce the progressive cell atrophy and protein loss. With 10 microM phenylephrine, cellular ATP content remained constant at 27 nmol/mg protein until day 15. The results indicate that agents which stimulate protein kinase C (alpha 1-agonists, phorbol esters) stimulate cell spreading, protein synthesis and long-term survival of cardiomyocytes in vitro.