Chances and limitations of isolated mouse heart models for investigating the endothelial glycocalyx1.

ABSTRACT

BACKGROUND: The endothelial glycocalyx plays a decisive role in maintaining vascular homeostasis. Previous animal models have mainly focused on in-vitro experiments or the isolated beating guinea pig heart. To further evaluate underlying mechanisms of up- and down regulation, knock-out animals seem to be a promising option. OBJECTIVE: Aim of the present study was to evaluate if an isolated mouse-heart model is suitable for glycocalyx research. METHODS: Isolated beating mouse hearts (C57/Bl6J) underwent warm, no-flow ischemia and successive reperfusion. Coronary effluent was analyzed by ELISA and Western blot for the glycocalyx core protein syndecan-1. Hearts were prepared for either immunofluorescence or electron microscopy and lysed for Western blot analysis. RESULTS: An endothelial glycocalyx covering the total capillary circumference and syndecan-1 were detected by electron and immunofluorescence microscopy. Ischemia/reperfusion seriously deteriorated both findings. Confoundingly, syndecan-1 was not detectable either in the coronary effluent or in the lysates of blood-free hearts by ELISA or Western blot technique. CONCLUSIONS: Blood vessels of mouse hearts contain an endothelial glycocalyx comparable to that of other animals also with respect to its core protein syndecan-1. But, for studies including quantification of intravascular soluble glycocalyx constituents, the amount of syndecan-1 in mouse hearts seems to be too low.