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

OBJECTIVE: Recent reports have demonstrated that long-term patency of the gastroepiploic artery (GEA) in coronary artery bypass grafting (CABG) is less satisfactory compared with the internal thoracic artery (ITA). However, the reason has not been fully elucidated. Angiotensin II is known to play an important role in the development of intimal hyperplasia, we hypothesized that the GEA is different from the ITA with respect to angiotensin II-forming ability. Accordingly, we measured activities of angiotensin II-forming enzymes, angiotensin-converting enzyme (ACE) and chymase, in human GEA and ITA. METHODS: Remnant of the GEAs and ITAs were obtained from 24 patients who underwent CABG in which both conduits were used simultaneously. Activities of ACE and chymase were measured by using the extract form the GEA or ITA. Sections of the GEA or ITA were immunohistochemically stained with anti-human chymase antibody. RESULTS: The ACE activity of the GEA (0.28+/-0.16 mU/mg protein) was greater than that of the ITA (0.18+/-0.11, p < 0.001). The chymase activity of the GEA (11.11+/-7.15 mU/mg protein) was also greater than that in the ITA (7.13+/-4.89, p < 0.001). The density of chymase-positive cells in the GEA (3.8+/-4.2 cells/mm2) was greater than that in the ITA (1.1+/-1.2, p < 0.01). CONCLUSION: Activities of both ACE and chymase were significantly greater in the GEA compared with the ITA. The GEA may be different from the ITA with respect to potential ability of angiotensin II-formation.

Effects of a phosphodiesterase 3 inhibitor, olprinone, on rhythmical change in tension of human gastroepiploic artery.

The gastroepiploic artery, used widely as a conduit in coronary artery bypass grafting, has high vasospasticity. The aims of this study were to examine the vasorelaxant effects of three phosphodiesterase 3 (PDE3) inhibitors, olprinone, milrinone and amrinone, on isolated gastroepiploic arterial preparations in comparison with a calcium channel blocker diltiazem, and to confirm the mRNA expression of PDE3A isoenzyme using reverse transcription-polymerase chain reaction (RT-PCR) in the human gastroepiploic artery isolated from stomach removed in cancer surgery. In endothelium-denuded gastroepiploic arterial preparations, phenylephrine (100 microM) produced spontaneous, rhythmical changes in tension consisting of repeated contraction and relaxation. Olprinone at a concentration of 10 microM (n=6) significantly inhibited the frequency (2.7+/-1.1 times/30 min vs. 6.2+/-0.7 times/30 min in the vehicle group), maximum tension (1.7+/-0.6 g vs. 3.6+/-0.6 g in the vehicle group) and minimum tension (0.6+/-0.2 g vs. 1.7+/-0.3 g in the vehicle group) of rhythmical changes. Such potency is comparable to that of diltiazem, but is stronger than milrinone and amrinone. RT-PCR using PDE3A- or PDE3B-specific oligonucleotide primer demonstrated the existence of PDE3A sequence in the gastroepiploic artery. These results suggest that olprinone, a potent PDE3A inhibitor, would be suitable for protecting against perioperative spasm during coronary artery bypass graft surgery.