A COMPARATIVE-STUDY OF THE CONCENTRATIONS OF HYPOXANTHINE, XANTHINE, URIC-ACID AND ALLANTOIN IN THE PERIPHERAL-BLOOD OF NORMALS AND PATIENTS WITH ACUTE MYOCARDIAL-INFARCTION AND OTHER ISCHEMIC DISEASES

The aim of this study was the elucidation of the role of the xanthine oxidoreductase in the purine metabolism in ischaemic diseases of man. The serum concentrations of hypoxanthine, xanthine, uric acid and alla ntoin were determined in peripheral blood samples from patients with a ngina pectoris, cerebral insult and myocardial infarction with thrombo lytic therapy and were compared with the concentrations obtained for h ealthy males and females. No significant differences were observed for the serum hypoxanthine concentrations, xanthine concentrations, the s um (hypoxanthine + xanthine) and the ratio (xanthine/hypoxanthine) bet ween the healthy males, healthy females, the patients suffering from a ngina pectoris and the patients suffering from cerebral insult. An inc rease of the serum xanthine concentration in patients with myocardial infarction indicates a significant metabolic involvement of xanthine o xidoreductase in this disease and therefore a possible role in the dev elopment of tissue damage in the postischaemic phase due to oxygen rad icals generated by the oxidase activity of this enzyme. The serum conc entrations of uric acid and allantoin showed no differences between an y of the studied groups. Study of the non-enzymatic oxidation of uric acid to allantoin by oxygen radicals, a relevant radical-scavenging me chanism in other diseases, provided no indication of an increased conc entration of oxygen radicals due to the xanthine oxidoreductase reacti on or other radical-producing mechanisms.