|Abstract||Cardiovascular disease is associated with endothelial dysfunction, a condition that results in the reduction of the vasodilator, nitric oxide (NO). Due to the difficulty in conducting in vivo analysis of EC function, previous research has focused on measuring the vascular endothelial (EC) and red blood cell (RBC) eNOS (or its mRNA) responsible for NO production primarily using animal models; however, harvesting of EC from human vasculature is possible. The purpose of this study was to determine if eNOS mRNA could be measured in EC taken from human veins. METHOD: Fifteen healthy males (n=8) and females (n=7) between the ages of 18 and 30 were cannulated in an antecubital vein, EC were harvested, and whole blood was drawn for RBC. The EC and RBC were placed into Trizol and mRNA isolated, followed by two step RT-PCR and analysis using the Delta Delta Ct method. RESULTS: Expression of eNOS mRNA in RBCs was detectable and was 3-fold greater in females compared to the males. The expression of eNOS mRNA in RBCs of the females using estrogen-based birth control (n = 3) was 3.5 fold greater than females not taking birth control. CONCLUSION: eNOS mRNA can be measured in EC taken from human veins.