AIMTo observe the change of cardiovascular endothelium's ultrastructure and its intercellular adhesion molecules-1 (ICAM-1) expression in rat after repetitive high positive acceleration (+ Gz) exposures and further to explore the mechanisms of myocardial injuries induced by high + Gz stress.

METHODSThirty male Wistar rats were randomly divided into three groups: control group, + 1Gz group and + 10Gz group (n = 10 for each). The rats of + 10Gz group were exposed to five plateaus at + 10Gz for 30s with + 1Gz 1 min intervals, 3 times a week, for 3 weeks, while rats of + 1Gz group subjected to + 1Gz for 5 mim daily. The control group didn't undergo acceleration stress. The rats were decapitated in the next day after the last centrifuge run and myocardium were immediately dissected from left ventricles for ultrastructural examination using transmission electron microscope and immunohistochemical staining of ICAM-1.

RESULTSThe ultrastructural changes of the cardiovascular endothelium were observed in rats of 10Gz group, including endothelium edema and platelet aggregating in lumen of blood vessel. Also, the expression of ICAM-1 in + 10Gz stressed rats increased significantly (P < 0.05). While there was no difference between control group and + 1Gz group in ultrastructure of cardiovascular endothelium and its ICAM-1 expression.

CONCLUSIONThe results suggested that repeated high + Gz exposures could injury cardiovascular endothelium of rat and increase ICAM-1 expression, which indicated cell adhesion molecules (CAMs) inducing inflammation took part in myocardial injuries induced by high + Gz stress.