Objective To discuss the influence of several physico-chemical factors existed in the surrounding environment on the endothelium function of pilots,submarine sailors and ground crew,so as to provide a basis for preventing the cardiovascular disease.Methods 48 submarine sailors(SM group),22 pilots(PI group)and 17 ground crew(control group),all of them were healthy males,were chosen as the subjects.The dynamic features of 3H-L-Arg in the platelets transportation were checked with isotope labeling technique.The yielded nitrite(NO-2),a product of NO metabolism,and the activity of NO synthase(NOS)in platelets were detected.Results In SM group,the ability of L-Arg transportation in platelets was much lower than that of both control group and PI group.The maximum transport velocity(Vmax)of SM group was lower by 31.4% than that of control group(P