AUGMENTED EFFECTS OF METHIONINE AND CHOLESTEROL IN DECREASING THE ELASTIC LAMINA WHILE THICKENING THE AORTIC-WALL IN THE RAT AORTA

1. Patients with an elevated plasma level of either homocysteine or ch olesterol are at increased risk of cardiovascular disease. Both methio nine, the precursor of homocysteine, and cholesterol are found primari ly in the same foods; therefore we investigated the effect of methioni ne feeding alone, cholesterol feeding alone, and both, on the thicknes s of the aortic wall and the aortic elastic lamina of normotensive ani mals. 2. Twenty normotensive rats were divided into four groups of fiv e animals. The following diet was administered for 15 weeks: normal ch ow; normal chow supplemented with 2% methionine; normal chow supplemen ted with 2% cholesterol; normal chow supplemented with 2% methionine+2 % cholesterol. 3. The results showed a 3-fold decrease (P < 0.003) in the aortic elastic lamina in the 2% methionine group and a 2.5-fold de crease in the 2% cholesterol group compared with the normal chow group . There was a 9-fold (P < 0.0003) decrease in the 2% methionine+2% cho lesterol group compared with the normal chow group. Furthermore, feedi ng with methionine plus cholesterol significantly increased aortic wal l thickness compared with the methionine group, cholesterol group or c ontrol. 4. These results demonstrate an augmented effect of cholestero l plus methionine in the deterioration of the aortic elastic lamina, a nd furthermore, the combination of these two agents increases the thic kness of the aortic wall. The results indicate a more important role f or these two agents in combination than for either agent alone.