Background: The present study was conducted to investigate the role of renal ischemia-reperfusion (IR) and angiotensin II (ANG II) on mRNA and protein levels of renal dihydrofolate reductase (DHFR), GTP-cyclohydrolase 1 (GTP- CH 1), and endothelial and inducible nitric oxide synthase (eNOS and iNOS, respectively). Methods: Male Wistar rats were sham operated or received IR (30 min occlusion, and reperfusion for 1 day). Each group was treated separately with water, angiotensin-converting enzyme inhibitor (ACEI) and ANG II receptor type 1 blocker (ARB) for 1 day before the sham operation or IR, and continuously for 1 day after the operation. The mRNA and protein levels were detected by RT-PCR and Western blot, respectively. Results: IR decreased DHFR mRNA and protein levels (p < 0.01), both of which were restored by ACEI or ARB, whereas GTP-CH 1 expression was unaltered. IR suppressed eNOS dimer while enhancing the monomer (p < 0.01). IR augmented iNOS mRNA, total iNOS protein and iNOS monomer (all p < 0.01) which were attenuated by ACEI or ARB. Conclusion: Our study is the first to demonstrate that the heightened ANG II in IR, via stimulation of ANG II receptor type 1, suppresses DHFR and eNOS dimer, while activating both iNOS mRNA and protein levels.

Keywords:
Angiotensin, Dihydrofolate reductase, GTP-cyclohydrolase 1, Nitric oxide synthase, Renal ischemia-reperfusion
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2008
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