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Sevoflurane preserves the endothelial glycocalyx against ischaemia-reperfusion injury.
BACKGROUND: Healthy vascular endothelium is coated by the glycocalyx, important in multiple endothelial functions, but destroyed by ischaemia-reperfusion. The impact of volatile anaesthetics on this fragile structure has not been investigated. We evaluated the effect of cardiac pre- and post-conditioning with sevoflurane on integrity of the endothelial glycocalyx in conjunction with coronary vascular function.
METHODS: Isolated guinea pig hearts perfused with Krebs-Henseleit buffer underwent 20 min stopped-flow ischaemia (37 degrees C), either without or with 1 MAC sevoflurane. This was applied for 15 min before, for 20 min after, or both before and after ischaemia. Transudate was collected for assessing coronary net fluid extravasation and histamine release by mast cells. Coronary release of syndecan-1 and heparan sulphate was measured. In additional experiments with and without continuous sevoflurane, cathepsin B and tryptase beta-like protease activity were measured in effluent. Hearts were perfusion-fixed to visualize the endothelial glycocalyx.
RESULTS: Ischaemia led to a significant (P<0.05) increase by 70% in transudate formation during reperfusion only in hearts without sevoflurane. This was accompanied by significant (P<0.05) increases in heparan sulphate (four-fold) and syndecan release (6.5-fold), with electron microscopy revealing massive degradation of glycocalyx. After ischaemia, histamine was released into transudate, and cathepsin B activity increased in effluent (P<0.05). Sevoflurane application attenuated all these changes, except for histamine release.
CONCLUSIONS: Sevoflurane protects the endothelial glycocalyx from ischaemia-reperfusion-induced degradation, with both preconditioning and rapid post-conditioning being successful. The mechanism seems to involve attenuation of lysosomal cathepsin B release and to be independent from tissue mast cell degranulation.
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