[Effects of burn serum on the endothelin receptor in cardiac microvascular endothelial cells]

Cardiac microvascular endothelial cells (CMEC) were harvested and cultured. Following incubation of CMEC with normal or burn rat (30% TBSA, II degree) serum for 12 hours, respectively, the affinity and binding capacity of endothelin (ET) receptor in CMEC membranes were investigated by radioligand binding assay. The results showed that only ETB receptor was distributed in rat CMEC membranes, with a maximal binding capacity (Bmax) of 142 +/- 27 fmol/mg protein and a dissociation constant (Kd) of 119 +/- 22 pmol/L. Burn rat serum induced an increase in Bmax of ETB receptor by 68%, without changing its Kd value, demonstrating that burn rat serum up-regulated ETB receptor. These results suggest that responsiveness to ET of microvascular endothelial cells may increase following burn.