Combined Use of Radioenzymatic Assay and High Pressure Liquid Chromatography for the Detection of Myocardial Xanthine Oxidase/Dehydrogenase

One of the current interests in xanthine oxidase (XO; EC 1.2.3.2; electron acceptor is O2, ref. 1) is its possible role in the initiation of atherosclerosis (refs. 2,3). To study the effects of bovine milk XO in rat heart, more knowledge is needed of the XO activity in this tissue, since data with respect to specific activity vary (refs.4–6). Several methods are available to measure XO activity (refs. 7,8). At the moment XO is thought to be present in mammalian tissues mainly as xanthine dehydrogenase (XD; EC 1.2.1.37; physiologic electron acceptor NAD+, ref. 1). The present paper describes the detection of XO and XD in rat heart by radioenzymatic assay in which the oxypurines are separated by high pressure liquid chromatography (HPLC).