Table 2. Effect of L-arginine on NADPH-diaphorase activity in the renal outer medulla of control and diabetic rats.

	C	D	C+A	D+A
PT (OS)	0.235±0.006 (n = 32)	0.241±0.007 (n = 40)	0.244±0.004 (n = 45)	0.298±0.009###&&& (n = 25)
CD (OS)	0.171±0.003 (n = 24)	0.142±0.008** (n = 15)	0.209±0.005*** (n = 24)	0.276±0.007###&&& (n = 31)
CD (IS)	0.157±0.007 (n = 16)	0.147±0.004 (n = 22)	0.187±0.003*** (n = 19)	0.158±0.004###& (n = 16)
THAL (IS)	0.255±0.004 (n = 30)	0.210±0.002*** (n = 32)	0.258±0.003 (n = 32)	0.221±0.002###& (n = 26)

C: control rats; D: diabetic untreated rats; D+A: diabetic rats treated with L-Arg; C+A: control rats treated with L-Arg. PT: proximal tubule; CD: collecting duct; THAL: thick ascending limb of Henle; OS: outer stripe; IS: inner stripe. NADPH-d staining values are expressed as optical density. Results are expressed as the mean ± SEM; “n” represents the total number of renal tubules analyzed. At least four animals of each group were used. Two-way ANOVA showed a statistically significant interaction between the effects of Diabetes and L-Arg treatment on NADPH-diaphorase activity in PT (p<0.001), CD (OS) (p<0.001), CD (IS) (p<0.05) and THAL (p<0.05). Bonferroni’s post-tests are showed in the table: **p<0.01 vs. C; ***p<0.001 vs. C; ^###p<0.001 vs. C+A; ^&p<0.05 vs. D; ^&&&p<0.001 vs. D.