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) rats created by inserting U-shaped polyurethane tubes in the left femoral arteries and veins. Three days after inserting the femoral AVS, the mean aortic blood flow rate in the abdominal aorta of the AVS rats was about 2.0 times 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 chain reaction (RT-PCR) data revealed that the mRNA expression level of the endothelial constitutive nitric oxide synthase (ecNOS) was increased in the aortas of the femoral AVS rats compared to that in the control rats. Western blot analysis using a monoclonal antibody against ecNOS revealed that the ecNOS protein levels were markedly increased in the aortas of femoral AVS rats, but ecNOS protein levels in aortas without endothelium were not significantly increased. Inducible nitric oxide synthase (iNOS) protein was not expressed in the aortic tissues with and without endothelium in the control rats. This iNOS expression was not increased by the high blood flow in the femoral AVS rats. These findings suggest that high blood flow could up-regulate the expression levels of ecNOS mRNA and proteins in femoral arteriovenous shunt rats.