Culture medium-dependent isoproterenol stability and its impact on DNA strand breaks formation and repair.

In vitro mechanistic research is mostly performed without taking into consideration the potential influence of cell culture media and/or their supplements and therefore, interactions between compounds of interest and medium ingredients may be overlooked. Isoproterenol (isoprenaline) is a synthetic catecholamine used as sympathomimetic drug that stimulates β-adrenergic receptors and is widely used in biomedical research. Clinical studies have shown that isoproterenol is rapidly metabolized in the human body with a plasma half-life of about 2-5 min. However, despite its use in many in vitro and ex vivo studies, the stability of isoproterenol in cell culture media has not been characterized. Our results show a decrease of isoproterenol concentration in RPMI medium but high stability of the compound in TexMACS medium. The isoproterenol oxidation product isoprenochrome forms during treatment in both media. However, isoprenochrome formation is significantly lower in TexMACS medium. The effective level of isoproterenol and the formation of oxidation products might explain the discrepancies observed in isoproterenol-induced genotoxicity and cytotoxicity.