Endothelium-dependent relaxation after short-term preservation of vascular grafts

As the integrity of graft endothelium seems to be essential to successful long-term patency in coronary operations, its preservation demands the utmost care. The aim of the present study was to investigate the effects of currently used solutions on endothelium-dependent relaxation after short-term storage of vessels at room temperature or at 4 °C. The infrarenal rat aorta was selected for study because its use enabled standardization of the investigation, which was performed in organ baths on 672 vessel segments from 112 Sprague-Dawley rats. Stable vasoconstriction was obtained with the thromboxane analogue U-46619. Acetylcholine was used to elicit endothelium-dependent relaxation. The results obtained for vessels preserved for 2 hours were compared with those for autologous vessels studied immediately after harvesting. Vessel contractility was unaffected by the preservation solutions, except in the Ringer's acetate group, where it was reduced by 50% (p < 0.05). Endotheliumindependent relaxation, tested with papaverine, was unaffected in all groups. Ringer's lactate, Krebs solution, and Perfadex (a low-potassium-dextran-glucose solu tion) did not significantly affect endothelium-dependent relaxation either at room temperature or at 4 °C, although a tendency to impaired relaxation was seen in these three groups after cold storage. Standard Ringer's solution and fresh heparinized blood each significantly reduced endothelium-dependent relaxation in vessels stored at room temperature (p < 0.05), but not in those stored at 4 °C. Endothelium-dependent relaxation was significantly reduced after storage in normal saline solution (p < 0.05) and in Ringer's acetate (p < 0.01), both at room temperature and at 4 °C. To conclude. Ringer's lactate, Krebs solution, and Perfadex were excellent solutions for short-term preservation of vessels, especially at room temperature. Heparinized blood and standard Ringer's solution were both acceptable storage media at 4 °C but not at room temperature, whereas normal saline solution and Ringer's acetate were unsuitable both at 4 °C and at room temperature for short-term preservation of vascular endothelium.