Erythrocyte sensitivity to oxidative stress during transient hyperhomocysteinemia was assessed by cumene hydroperoxide-induced α-tocopherol consumption before and after methionine load in 31 healthy subjects and 23 patients with coronary artery disease.
Decreased sensitivity to oxidative challenge (“Type-1” response) after methionine load was more frequent in healthy subjects (35 % vs 13 % in patients), while increased sensitivity (“Type-2” response) was more frequent in patients (22 % vs 6 % in healthy subjects). No variation in sensitivity to oxidative challenge throughout the loading test (“Non-variant” response) was detected in either group (58 % in healthy subjects and 65 % in patients). The distribution of these responses was significantly different between healthy subjects and patients and independent of basal and post-load increase in homocysteine. Plasma lipoperoxides, erythrocyte α-tocopherol and glutathione content before methionine load were significantly different between patients and healthy subjects; however only the redox potential of the GSSG/GSH couple was significantly different in the different groups of response.
The higher frequency of “Type-2” response in patients with respect to healthy subjects suggests that methionine load reveals individual factors that may contribute to the pathogenesis of atherosclerosis.