Use of superoxide dismutase and catalase to protect catecholamines from oxidation in tissue culture studies.

A new enzymatic approach for the prevention of catecholamine oxidation that is particularly useful for studies with cultured cells is described. Catecholamine oxidation was assayed by acid alumina chromatography using a modified procedure that yields greater than or equal to 90% column recovery of catecholamine concentrations as low as 1.0 nM. Addition of superoxide dismutase and catalase (10-25 micrograms/ml each) results in virtually complete inhibition of catecholamine oxidation under a variety of experimental conditions. Although superoxide dismutase could prevent catecholamine oxidation, addition of catalase helped prevent the cytotoxicity of oxidative products. When used together, these enzymes have no effect on cell growth, hormonal response, or radioligand binding to membrane beta-adrenergic receptors in the murine S49 lymphoma cell, a widely used model system for studying catecholamine action. Combined use of superoxide dismutase and catalase offers nonperturbing, long-lasting protection of catecholamines in studies with cells in vitro. This method provides a useful alternative to ascorbic acid, chelators, or reducing agents which have previously been used to prevent catecholamine oxidation but which may have other effects on cultured cells and on membrane proteins.