[Free radical toxicity in coronary insufficiency]

A number of experimental models have shown abnormally high concentrations of cytotoxic oxygen derived free radicals (FR), and decreased concentrations of protecting anti-oxidising enzymes during myocardial ischaemia. These FR react with the unsaturated lipids of the cell membrane, a phenomenon known as membrane lipidoperoxidation (MLP) to produce very cytotoxic endoperoxides. We studied an intermediary product of MLP, malondialdehyde (MDA) in 10 patients with a preinfarction syndrome (Group 1) and 8 patients in the acute phase of myocardial infarction (Group 2). Plasma MDA was measured on admission (P2) and 12th day (P3). There was a significant elevation of MDA in both groups at P1 and P2 (p less than 0.01) compared with results obtained in 15 normal control subjects of the same age. The MDA concentration on the 12th day in the infarct group was significantly lower (189 +/- 41 ng/ml, p less than 0.01) compared with the highest value observed either on admission or on the 5th day (peak MDA 258 +/- 62 ng/ml). The difference between MDA concentrations on the 12th day and peak MDA was less striking in Group 1. None of the patients in Group 2 had a recurrence of chest pain after the initial phase of infarction and the residuals MDA concentration (P3) was similar to control values (181 +/- 27 ng/ml). On the other hand, in the preinfarction syndrome group, 4 patients had persistent unstable angina on the 12th day and their MDA concentrations remained high (250 +/- 42 ng/ml). This was interpreted as reflecting continuing MLP in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)