Long-term preservation of vascular endothelium and smooth muscle

This study was performed in organ baths on 400 ring segments of infrarenal aorta taken from 40 Sprague-Dawley rats that had been randomized into five groups. Contractility was tested with the thromboxane analogue U-46619. Acetylcholine was used to elicit endothelium-dependent relaxing factor (EDRF). The results obtained from vessels preserved at 4°C for 6, 12, 24, and 36 hours were compared with those from autologous vessels studied immediately after harvesting. Vessels preserved in Euro-Collins solution showed a 46% (p < 0.01) decrease in contractility after 12 hours of storage; after 24 hours only weak contractions could be elicited, and after 36 hours they had lost their ability to contract. The EDRF function was slightly reduced after 12 hours and could not be investigated after 24 and 36 hours. With the University of Wisconsin solution (UW) and the low-potassium-dextran-glucose solution Perfadex no decrease in contractility was seen in the first 24 hours, but at 36 hours the vessels preserved in UW had lost 40% (p < 0.01) and those preserved in Perfadex 30% (p < 0.05) of their contractility. The EDRF function was significantly reduced by about 15% after 6, 12, and 24 hours in both the UW and the Perfadex groups. At 36 hours, vessels stored in Perfadex had lost 41% (p < 0.001) and those stored in UW 17% (p < 0.01) of their EDRF function. Vessels stored in Krebs solution (the only solution containing calcium) manifested no reduction in contractility throughout the 36-hour test period, but a marked decrease in EDRF function was seen at 6 hours (12%; p < 0.05), 12 hours (31%; p < 0.05), 24 hours (68%; p < 0.001), and 36 hours (86%; p < 0.001). Vessels stored in heparinized blood maintained good contractility the first 24 hours, but after 36 hours a 30% (p < 0.05) loss of contractility was seen; the EDRF function was good for a period of up to 12 hours, but showed a decrease in relaxation capacity after 24 hours (39%; p < 0.05) and after 36 hours (70%; p < 0.001). To conclude, UW and Perfadex gave good preservation for 24 hours. After 36 hours, UW was slightly better for the endothelium whereas Perfadex was slightly better for the smooth muscle function. Euro-Collins solution was not a suitable solution for long-term preservation of blood vessels. Considering the excellent results obtained with Krebs solution regarding contractility, we suggest that the addition of calcium to UW and Perfadex will improve their ability to preserve smooth muscle function during prolonged storage.