Effect of ischemia-reperfusion on renal expression and activity of N(G)-N(G)-dimethylarginine dimethylaminohydrolases.
BACKGROUND
Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase. It is degraded by the enzyme dimethylarginine dimethylaminohydrolase (DDAH).


METHODS
Rats (n = 50) underwent to 45 min of renal ischemia followed by 30 min, 1 h, and 3 h of reperfusion. Expression of endothelial nitric oxide synthase, inducible nitric oxide synthase, DDAH-1, DDAH-2, renal DDAH activity, plasma NO2(-)/NO3(-), and ADMA levels were evaluated.


RESULTS
Inducible nitric oxide synthase expression increased, as confirmed by both plasma (11.89 +/- 1.02, 15.56 +/- 0.93, 11.82 +/- 0.86, 35.05 +/- 1.28, and 43.89 +/- 1.63 nmol/ml in the control, ischemic, 30-min, 1-h, and 3-h groups, respectively) and renal (4.81 +/- 0.4, 4.85 +/- 1, 9.42 +/- 0.7, 15.42 +/- 0.85, and 22.03 +/- 1.11 nmol/mg protein) formations of NO2(-)/NO3(-). DDAH-1 expression decreased after reperfusion, whereas DDAH-2 increased after 30 min, returning to basal levels after 3 h. Total DDAH activity was reduced during all times of reperfusion. Both plasma (0.41 +/- 0.03, 0.43 +/- 0.05, 0.62 +/- 0.02, 0.71 +/- 0.02, and 0.41 +/- 0.01 nmol/ml in the control, ischemic, 30-min, 1-h, and 3-h groups, respectively) and renal (1.51 +/- 0.01, 1.5 +/- 0.01, 1.53 +/- 0.01, 2.52 +/- 0.04, and 4.48 +/- 0.03 nmol/mg protein in the control, ischemic, 30-min, 1-h, and 3-h groups, respectively) concentrations of ADMA increased.


CONCLUSIONS
Results suggest that ischemia-reperfusion injury leads to reduced DDAH activity and modification of different DDAH isoform expression, thus leading to increased ADMA levels, which may lead to increased cardiovascular risk.
Li Volti
Giovanni
G
Department of Biological Chemistry, Medical Chemistry and Molecular Biology, University of Catania, Italy. livolti@unict.it
Sorrenti
Valeria
V
Acquaviva
Rosaria
R
Murabito
Paolo
P
Gullo
Antonino
A
Barcellona
Maria Luisa
ML
Galvano
Fabio
F
Rodella
Luigi
L
Rezzani
Rita
R
Vanella
Luca
L
Tringali
Giovanni
G
Caruso
Massimo
M
Gazzolo
Diego
D
Di Giacomo
Claudia
C
D000581:Amidohydrolases / Q000096:biosynthesis*; D000818:Animals; D004789:Enzyme Activation / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D007511:Ischemia / Q000201:enzymology* / Q000473:pathology; D007668:Kidney / Q000098:blood supply* / Q000201:enzymology* / Q000473:pathology; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D051381:Rats; D015424:Reperfusion
D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D000581:Amidohydrolases; C059999:dimethylargininase