Related Experiment Videos
Endothelial function of human gastroepiploic artery. Implications for its use as a bypass graft
G S O'Neil1, A H Chester, S P Allen
1National Heart and Lung Institute, Harefield Hospital, Middlesex, England.
Insights
The gastroepiploic artery
Area of Science:
- Cardiovascular Biology
- Vascular Surgery
- Endothelial Function
Background:
- The human gastroepiploic artery is an emerging conduit for coronary artery bypass grafting.
- Endothelial function is crucial for graft patency, influencing vasoactive substance release.
- Variations in endothelial function may explain differing patency rates among bypass grafts.
Purpose of the Study:
- To investigate the endothelial function of the human gastroepiploic artery.
- To assess the role of nitric oxide and prostacyclin in gastroepiploic artery vasodilation.
- To compare the vasodilatory capacity of the gastroepiploic artery with other bypass grafts.
Main Methods:
- Studied endothelium-dependent relaxations to substance P in human gastroepiploic artery.
- Utilized L-NG-monomethyl-arginine to inhibit nitric oxide synthesis.
- Measured cyclic guanosine 3',5'-monophosphate levels via radioimmunoassay.
- Assessed effects of indomethacin on vascular tone.
Main Results:
- Substance P induced significant endothelium-dependent relaxation.
- Nitric oxide synthesis inhibition attenuated relaxation, indicating its role.
- Gastroepiploic artery showed higher cyclic guanosine 3',5'-monophosphate levels than internal mammary artery or saphenous vein.
- Evidence of synergy between endothelium-derived relaxing factor and prostacyclin was observed.
Conclusions:
- The gastroepiploic artery endothelium possesses a robust capacity for secreting vasodilators.
- This vessel also demonstrates significant potential for inhibiting platelet activity.
- These endothelial properties likely contribute to the long-term patency of gastroepiploic artery grafts.
Abstract:
The human gastroepiploic artery has been used as a coronary artery bypass conduit in a limited number of clinical studies. It has been postulated that the capacity of the endothelium to release vasoactive substances may contribute to differing patency rates observed in established bypass grafts. We have now examined endothelial function in the human gastroepiploic artery. Endothelium-dependent relaxations to substance P were observed. A maximum relaxation of 83.25% +/- 8.2% (mean +/- standard error) was attenuated to 48.5% +/- 16.4% in the presence of L-NG-monomethyl-arginine, a specific inhibitor of endogenous nitric oxide synthesis. Removal of the endothelium abolished the relaxations. With a specific radioimmunoassay, concomitant changes in levels of cyclic guanosine 3',5'-monophosphate, the second messenger that elicits smooth muscle relaxation after release of the endothelium-derived relaxing factor, were measured. It was found that the gastroepiploic artery had significantly higher resting and stimulated levels of cyclic guanosine 3',5'-monophosphate than either the internal mammary artery or the saphenous vein. In the presence of the cyclooxygenase inhibitor indomethacin, and indomethacin plus L-NG-monomethylanginine, the maximum relaxation was decreased to 70% +/- 9.5% and 59% +/- 10.8%, respectively. Our data demonstrate that endothelium-derived relaxing factor and prostacyclin may exhibit synergy in the control of vascular tone in this vessel. It is concluded that the endothelium of the gastroepiploic artery has a strong capacity to secrete vasodilators and inhibitors of platelet activity. This could have important influence on long-term patency.