Effect of high blood flow on the expression of endothelial constitutive nitric oxide synthase in rats with femoral arteriovenous shunts

The effect of high blood flow on the expression of endothelial nitric oxide synthase has been investigated in the femoral arteriovenous shunt (AVS) ra ts created by inserting U-shaped polyurethane tubes in the left femoral art eries and veins. Three days after inserting the femoral AVS, the mean aorti c blood flow rate in the abdominal aorta of the AVS rats was about 2.0 time s higher than that in the control rats (110.0 +/- 8.4 ml/min vs 52.7 +/- 2. 7 ml/min, p < 0.001). The competitive reverse transcriptase-polymerase chai n reaction (RT-PCR) data revealed that the mRNA expression level of the end othelial constitutive nitric oxide synthase (ecNOS) was increased in the ao rtas of the femoral AWS rats compared to that in the control rats. Western blot analysis using a monoclonal antibody against ecNOS revealed that the e cNOS protein levels were markedly increased in the aortas of femoral AVS ra ts, but ecNOS protein levels in aortas without endothelium were not signifi cantly increased. Inducible nitric oxide synthase (iNOS) protein was not ex pressed in the aortic tissues with and without endothelium in the control r ats. This iNOS expression was not increased by the high blood flow in the f emoral AVS rats. These findings suggest that high blood flow could up-regul ate the expression levels of ecNOS mRNA and proteins in femoral arterioveno us shunt rats.