[Dynamic changes of endothelin in sera of rats at early burn stage and its effects on endothelial cell permeability...

The dynamic changes of endothelin in sera of early burnt rats and the effects of endothelin-1 on the permeability of vascular endothelial cells were investigated. In the early phase of 30% (II degree) total body surface area (TBSA) burn rat model, we measured the concentration of endothelins in plasma, the water contents in main organs and the permeability of endothelial monolayer cultured on micropore membrane to Hank's solution or 5 g/L albumin Hank's solution. Endothelin concentration in burnt rat sera was firstly increased dramatically, showing a peak at 6 hours postburn, and then remained significantly higher than the basic level (P < 0.01). The changes of endothelin were correlated with the alteration in water contents in main organs after burn. Moreover, if the cultured endothelial cells were exposed to 0, 1, 10, 100 nmol/L endothelin 1 for 60 min, it was found that the filtration volume (Jv) and the filtration coefficient (Kf) of endothelial monolayer were significantly enhanced as determined by either Hank's or albumin (5 g/L) perfusion, while the osmotic reflection coefficient (sigma) (to protein) decreased in a dose-dependent pattern. The present results suggest that the postburn elevated endothelin may not only mediate the blood flow distribution via potent vasoconstriction, but also directly increase the vascular permeability. The mechanism(s) of the latter event needs to be further clarified.