mRNA and nNOS protein nor inducible NOS (iNOS) mRNA and iNOS protein in the kidneys

Nitric oxide (NO) is produced in the vascular endothelium and is a potent vasodilator substance that participates in the regulation of local vascular tone. Exercise causes peculiar changes in systemic and regional blood flow, i.e. an increase of systemic blood flow and a redistribution of local tissue blood flow, by which the blood flow is greatly increased in the working muscles, whereas it is decreased in some organs such as the kidney and intestine. Thus, we hypothesized that exercise causes a tissuespecific change of NO production in some internal organs. We studied whether exercise affects expression of NO synthase (NOS) mRNA and protein, NOS activity, and tissue level of nitrite (NO2) /nitrate (NO3) (i.e., levels of NOx: stable end products of NO) in the kidneys (in which the blood flow during exercise is decreased) and lungs (in which the blood flow during exercise is increased with the increase of cardiac output) of rat. Rats ran on a treadmill for 45 min at a speed of 25 m/min. Immediately after this exercise, the kidneys and lungs were quickly removed. Control rats remained at rest during this 45min period. The expression of endothelial NOS (eNOS) mRNA in the kidneys was markedly lower in the exercise rats than in the control rats, whereas that in the lungs was significantly higher in the exercise rats than in the control rats. Western blot analysis confirmed downand up-regulation of eNOS protein in the kidney and lung, respectively, after exercise. On the other hand, neither the expression of neuronal NOS (nNOS) mRNA and nNOS protein nor inducible NOS (iNOS) mRNA and iNOS protein in the kidneys and lungs differed between the exercise and control rats. The NOS activity in the kidney was significantly lower in the exercise rats than in the control rats, whereas that in the lung was significantly higher in the exercise rats than in the control rats. On the other hand, the iNOS activity in the kidneys and lungs did not differ between the exercise rats and control rats. The tissue NOx level in the kidneys was markedly lower in the exercise rats, whereas that in the lungs was significantly higher in the exercise rats. The present results show that the production of NO is markedly changed tissuespecifically in the kidney and lung by exercise. by 10.0.33.1 on M ay 1, 2017 http://jaysiology.org/ D ow nladed fom FINAL ACCEPTED VERSION JAP-00269-2002. R1 page 3