Comparative analysis of the hydrogen sulphide pathway in internal thoracic artery and radial artery

OBJECTIVES: The molecular basis supporting the superiority of the left internal thoracic artery (LITA) as a bypass conduit is limited. This study was conducted to compare the expression and localization of hydrogen sulphide synthesizing enzymes in LITA and radial artery (RA). METHODS: Nineteen patients who underwent coronary artery bypass grafting using LITA and RA were enrolled. The remnant LITA and RA were collected to measure the expression levels of 3 hydrogen sulphide-producing enzymes: cystathionine β-synthase, cystathionine γ-lyase and 3-mercaptopyruvate sulphurtransferase using quantitative real-time polymerase chain reaction. Expression levels of these enzymes in the LITA and RA were compared in each subject. The expression and localization patterns of the enzymes were also analysed by immunohistochemistry. RESULTS: The mRNA expression of the cystathionine β-synthase was greater in the LITA than in the RA (P = 0.033), whereas the expression levels of the other 2 enzymes did not significantly differ between the 2 arteries. The immunohistochemistry analysis demonstrated greater expression of the cystathionine β-synthase in the LITA than in the RA (P = 0.006). This protein was present in both tunica intima and tunica media of the LITA, although it was present only in the tunica media of the RA. Localization patterns of the other 2 enzymes were not different between LITA and RA. CONCLUSIONS: Expression levels of the mRNA and protein of cystathionine β-synthase were significantly greater in LITA than in the RA. These findings might be a factor that affects the superior patency rate of LITA.