A PILOT-STUDY OF BLOOD ANTIOXIDANT AND FREE-RADICAL MARKER PROFILES IN PATIENTS AWAITING CORONARY-ARTERY BYPASS-GRAFTING

Coronary artery bypass grafting (CABG) carries a high risk of acute pa ncreatitis. We report a pilot study to investigate whether pre-existin g oxidative stress might underlie this susceptibility, in that a burst of free radical activity not only accompanies the reperfusion stage o f CABG but seems to be a pivotal step in the pathogenesis of pancreati tis. Samples of peripheral venous blood were obtained on the morning o f surgery from 8 consecutive patients (age, median and range, 62, 35-7 0 years) with >75% stenosis in at least three coronary vessels and a f urther 8 (64, 49-70 years) who had received 1200 mg allopurinol in div ided doses in the previous 48 h: the results were compared with profil es of 8 healthy controls (56, 50-60 years) with normal exercise EGG. N one of the patients or controls currently smoked cigarettes and the ma jority drank alcohol on a social basis. Compared with controls, untrea ted patients had lower levels of glutathione (P < 0.001) and ascorbate (P < 0.05) in plasma, alpha-tocopherol (vitamin E as molar ratio of c holesterol, P < 0.025) and B-carotene (P < 0.05) in serum. There was n o difference in serum selenium levels, but values in patients and cont rols were lower than in younger controls from this area (P < 0.02), Sa mples from the patients contained higher concentrations of lipid perox ides than control samples (P < 0.025) but there was no evidence of exc essive isomerisation of linoleic acid or oxidation of ascorbate and er ythrocytes showed normal ATP and energy charge with no increase in mem brane lipid peroxidisability, Treatment with allopurinol did not alter this pattern, such that the ratio of oxidised to total glutathione in plasma was higher among the 16 patients than 8 controls (P < 0.025). Habitually inadequate intakes are the best explanation for the patient s' deficits in aqueous phase antioxidants; prescribed low cholesterol diets would exacerbate any prior insufficiency of lipid-phase antioxid ants. Correction of these deficits during the months lending up to sur gery should reduce the risk of CABG-induced acute pancreatitis.