Decreased Formation of Nitric Oxide in Rats Treated with FK506 / 대한신장학회잡지

ABSTRACT

The present study was aimed at investigating whether FK506 alters the regulation of nitric oxide(NO) system. Male Sprague-Dawley rats were treated with FK506(1 mg/kg/day, i.m.) for 3 weeks. Control group was without treatment of FK506. Plasma levels and urinary excretion of NO metabolites(nitrite/nitrate, NOx) were measured. The protein expression of NO synthases(NOS) and tissue contents of NOx were determined in the kidney and thoracic aorta. The aorta was also examined of its changes in isometric tension in responses to acetylcholine and sodium nitroprusside. The arterial pressure did not significantly differ between FK506-treated and control groups. Plasma NOx levels remained unaltered, while urinary NOx excretion was significantly decreased in FK 506-treated group. Tissue contents of NOx were significantly decreased, although the expression of ecNOS and iNOS proteins was significantly altered neither in the kidney nor in the aorta. Acetylcholine-induced relaxation of the isolated aortic ring was significantly attenuated, whereas sodium nitroprusside-induced relaxation was not significantly affected. These results suggest that FK506 decreases the tissue contents of NO, without significantly affecting the expression of NOS.