Human gastroepiploic artery has greater chymase activity than the internal thoracic artery

Area of Science:

• Cardiovascular Surgery
• Vascular Biology
• Biochemistry

Background:

• Long-term patency of the gastroepiploic artery (GEA) in coronary artery bypass grafting (CABG) is often less satisfactory than the internal thoracic artery (ITA).
• Intimal hyperplasia, a key factor in graft failure, is influenced by angiotensin II.
• The underlying reasons for GEA's reduced patency compared to ITA remain incompletely understood.

Purpose of the Study:

• To investigate potential differences in angiotensin II-forming enzyme activity between human GEA and ITA.
• To test the hypothesis that GEA has a greater capacity for angiotensin II formation than ITA.

Main Methods:

• Human GEA and ITA samples were obtained from 24 patients undergoing simultaneous CABG.
• Enzyme activities of angiotensin-converting enzyme (ACE) and chymase were quantified in tissue extracts.
• Immunohistochemical staining was performed to assess chymase-positive cell density in both artery types.

Main Results:

• GEA exhibited significantly higher ACE activity (0.28±0.16 mU/mg protein) compared to ITA (0.18±0.11 mU/mg protein, p < 0.001).
• Chymase activity was also significantly greater in GEA (11.11±7.15 mU/mg protein) than in ITA (7.13±4.89 mU/mg protein, p < 0.001).
• The density of chymase-positive cells was higher in GEA (3.8±4.2 cells/mm²) versus ITA (1.1±1.2 cells/mm², p < 0.01).

Conclusions:

• Both ACE and chymase activities are significantly elevated in the GEA relative to the ITA.
• These findings suggest that GEA possesses a greater intrinsic potential for angiotensin II formation.
• This enhanced angiotensin II-forming ability may contribute to the observed differences in long-term patency between GEA and ITA in CABG procedures.