Morphological and Functional Alterations in Endothelium, Smooth Muscle, and Nerve Fibers in Rabbit Aorta after Storage at 4°C

Abstract

Structural and implied functional changes in endothelial cells (EC), smooth muscle cells (SMC), and nerve fibers (NF) in rabbit aorta were studied after storage in cold Krebs solution. Rings from the thoracic aorta were stored for 2, 4, 6, and 8 days in a refrigerator at 4°C. Subsequently they were examined after 6 h in an organ bath at 37°C and processed for transmission electron microscopy. The earliest and most prominent structural changes were observed in NF and varicosities. These changed after 2 days and were completely destroyed after 6 days. Less remarkable changes in both the intensity and the timeliness of alterations were found in EC. The majority of them showed changes after 4 days. After 8 days they were seriously destroyed, but still formed a relatively continuous layer. The most resistant cells were SMC, showing only slight alterations during the whole period. Contraction of aortic rings in response to transmural nerve stimulation (8 Hz) gradually decreased with the length of cold storage. After 4 days contraction was about 10% of the control value, while after 6 days it was entirely abolished. Maximal relaxation of noradrenaline-precontracted rings in response to acetylcholine was decreased to 46% after 4 days of storage, while after 8 days it was only 15% of the control value. The contractile response of aorta to exogenous noradrenaline did not change during the whole period except for Day 4 when the response was significantly increased. These results showed the different susceptibilities of the EC, the SMC and the NF of the thoracic aorta to cold storage at 4°C (NF > EC > SMC). The observed structural changes were in close agreement with their functional expressions.