Elevated homocysteine serum level is associated with low enrichment of homocysteine in coronary arteries of patients with coronary artery disease.

In the present study, we sought to investigate whether elevated serum levels of homocysteine (Hcy), predisposing to endothelial dysfunction during progression of atherosclerosis, were paralleled by increased Hcy concentrations in human coronary arteries. Paraffin sections of coronary arteries were obtained from explanted hearts of cardiac transplant recipients suffering from coronary artery disease (CAD, n=32, mean age=56.6+/-6.8), and from heart donors where transplantation was not performed due to organization-related circumstances (Co, n=6, mean age 25.0+/-10.6), and characterized immunohistochemically for Hcy, CD68, and smooth muscle alpha-actin. Although the CAD group presented with high serum Hcy levels (27.7+/-12.8 micromol/l), the media and intimal layers containing the endothelium showed the lowest enrichment of Hcy (media: 20.8+/-4.4%; intima: 6.1+/-2.3%). Surprisingly, the control group revealed an extensive Hcy enrichment, co-localizing with vascular smooth cells (media: 32.3+/-14.0%; intima: 7.0+/-2.0%). In conclusion, we have provided evidence for a reverse relation between Hcy serum concentration and enrichment of Hcy in coronary arteries of patients with severe CAD, suggesting that Hcy is not likely to be involved directly in atheromatosis development of coronary arteries.