Ethylene glycol permeation and toxicity in the rabbit common carotid artery

The rate of permeation of ethylene glycol (EG) and the maximum concentration that can be tolerated without functional damage was measured in the rabbit common carotid artery. Pairs of arteries were perfused on ice, one (the control) with a high K+ balanced salt solution containing 100 mM TES (CPTES), and the other with ethylene glycol/CPTES solutions. The concentration of EG was increased in a stepwise manner in order to reduce osmotically induced changes in endothelial cell volume. The final concentration was 10, 20, or 40% EG (w/w). After exposure for 20 min, the EG was then removed at room temperature using stepwise decreasing concentrations of ethylene glycol in the presence of 3% mannitol. After this, the contractile function of the smooth muscle was tested at 37 degrees C with noradrenaline and the integrity of the endothelium was assessed structurally by vital staining and functionally by its capacity to produce endothelium-derived relaxation factor in response to administration of acetylcholine. The tissue concentration reached 8.6% after 30 min of exposure to 10% EG. The contractile function of the smooth muscle was unaffected by EG at all concentrations. There was a significant (50%) reduction in the ACh-induced relaxation of contracted arteries after exposure to 40% EG (P < 0.02) but this was not associated with any detectable loss of cells or damage to the endothelium. It was concluded that EG warrants further investigation as a cryoprotectant for blood vessels.