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Functional changes in canine saphenous veins after cryopreservation
J R Elmore1, P Gloviczki, K G Brockbank
1Section of Vascular Surgery, Mayo Clinic, Rochester, MN.
Summary
Cryopreservation of canine saphenous veins impairs smooth muscle contraction and nerve terminal function. While endothelium-derived relaxing factors and prostanoids are produced, nitric oxide synthesis may be reduced, impacting graft patency.
Area of Science:
- Vascular biology
- Cryobiology
- Surgical research
Background:
- Cryopreservation is a method for preserving biological tissues, but its effects on vascular function require detailed investigation.
- Understanding the impact of cryopreservation on vein grafts is crucial for improving their long-term patency in arterial reconstruction.
Purpose of the Study:
- To assess the functional changes in endothelium, smooth muscle, and nerve terminals of cryopreserved canine saphenous veins.
- To evaluate the impact of cryopreservation on the release of vasoactive substances and neurotransmitter uptake.
Main Methods:
- Canine saphenous veins were cryopreserved at -196°C for at least 3 weeks.
- Vascular rings, with and without endothelium, were subjected to contractile and relaxant responses to various stimuli (KCl, adrenergic agonists, calcium ionophore).
- Nerve terminal function was assessed via norepinephrine uptake, and mediator production (prostacyclin, endothelin) was measured.
Main Results:
- Cryopreserved veins exhibited reduced maximal contraction to KCl and alpha-adrenergic stimulation compared to fresh veins.
- Endothelium-dependent relaxations mediated by nitric oxide (NO) synthesis were impaired in cryopreserved veins, though prostacyclin production was elevated.
- Cocaine-sensitive norepinephrine uptake was reduced, indicating altered nerve terminal function.
Conclusions:
- Cryopreservation significantly alters the functional properties of canine saphenous veins, affecting smooth muscle contractility and nerve terminal integrity.
- While cryopreservation impacts NO synthesis, it may preserve or enhance prostacyclin release.
- These functional changes may compromise the patency of cryopreserved veins when used as arterial grafts.