Regional specific modulation of the glycocalyx and smooth muscle cell contractile 1 apparatus in conduit arteries of tail - suspended rats

28 The glycocalyx is a key mechanosensor on the surfaces of vascular cells (EC/SMC), 29 and recently, we reported that the redistribution of the hemodynamic factors in 30 tail-suspended (TS) hindlimb-unloaded rats induces the dimensional adaptation of the 31 endothelial glycocalyx in a regional-dependent manner. In the present study, we 32 investigated the coverage and gene expression of the glycocalyx and its possible 33 relationship with smooth muscle contractility in the conduit arteries from the TS rats. 34 The coverage of the glycocalyx, determined by the area analysis of the fluorescein 35 isothiocyanate-labeled wheat germ agglutinin (WGA-FITC) staining to the 36 cryosections of rat vessels, showed a 27.2% increase in the common carotid artery, a 37 13.3% and 8.0% decrease in the corresponding abdominal aorta and the femoral artery 38 after 3 weeks of tail suspension. The relative mRNA levels of syndecan-2, 3, 4, 39 glypican-1, smooth muscle protein 22 (SM22), smoothelin (SMTN), and calponin 40 were enhanced to 1.40, 1.53, 1.70, 1.90, 2.93, 2.30, and 5.23-fold respectively in the 41 common carotid artery of the TS rat. However, both glycocalyx related genes and 42 smooth muscle contractile apparatus were totally or partially down-regulated in the 43 abdominal aorta and femoral artery of the TS rat. A linear positive correlation between 44 the normalized coverage of glycocalyx and normalized mRNA levels of SM22, 45 SMTN, and calponin exists. These results suggest the regional-dependent adaptation 46 of the glycocalyx in simulated microgravity condition, which may affect its 47 mechanotransduction of shear stress to regulate the contractility of the smooth muscle, 48 finally contributing to postspaceflight orthostatic intolerance. 49 by 10.0.33.6 on A ril 2, 2017 http://jaysiology.org/ D ow nladed fom