Endothelium-dependent relaxation in rabbit aorta after cold storage

Abstract

The extent of preservation of endothelial, smooth muscle and neurogenic function following cold storage was studied in rabbit thoracic aorta. Relaxation responses to acetylcholine and sodium nitroprusside were compared between fresh aortic rings and rings that had been stored in a refrigerator for 2–8 days at 4°C. In fresh aortic rings, the addition of acetylcholine to precontracted vessels resulted in dose-dependent relaxation. The magnitude of relaxation was gradually decreased after 4–8 days of cold storage. Relaxation in response to sodium nitroprusside did not change. Following cold storage contractions of aortic rings in response to noradrenaline and phenylephrine were not reduced. Contractile responses induced by transmural nerve stimulation were gradually attenuated with the length of cold storage. Electron microscopy after 4 days showed partial damage of endothelial cells (slightly vacuolized mitochondria). After 8 days, endothelial cells were destroyed; only membranous material was present. The structure of smooth muscle cells was only partially changed even after 8 days. Sympathetic nerve endings on the 4th day were partially, but on the 8th day completely destroyed. These results suggest that after cold storage of rabbit aorta, the gradual reduction of endothelium-dependent relaxation is probably caused by a decrease in production of the endothelium-derived relaxing factor due to the destruction of endothelial cells.