Beschreibung:
<jats:p><i>Background:</i><i>L</i>-Arginine (<i>L</i>-Arg), a substrate of nitric oxide synthases, improves renal function in ischemic acute renal failure (iARF). We evaluated whether <i>L</i>-Arg improves renal morphology and cell survival in the course of iARF. <i>Methods and Results:</i> iARF was induced in rats by bilateral clamping of renal arteries for 45 min. <i>L-</i>Arg was applied intraperitoneally during clamping, and orally during 14 days of follow-up. Morphology and cell survival of renal cortical and medullar tissue was analyzed on days 1, 3, 7, and 14 of follow-up, using toluidine blue staining and immunohistochemistry of perfusion-fixated tissue, and Western blot analysis of tissue homogenate. Renal tubular injury showed typical features of necrosis and was most severe on days 1 and 3 after clamping, predominantly in S3 segments, with almost complete recovery by day 14. Enhanced medullar monocyte infiltration, determined by ED-1 expression as well as by immunohistochemistry, and enhanced expression of proliferating cell nuclear antigen (PCNA), indicative of proliferation and regeneration, accompanied these morphological changes. Compared to controls, <i>L</i>-Arg had no impact on renal morphology, ED-1, and PCNA expression. Furthermore, expression of markers of apoptosis Bcl-2, Bax, and cleaved caspase-3 was only slightly increased in iARF rats, compared to sham-operated animals, and was also not influenced by <i>L</i>-Arg. <i>Conclusion:</i> Despite its repeatedly reported positive impact on renal function as also shown in our model, <i>L</i>-Arg does not alter cell death and proliferation in the course of iARF in our model. Thus, different mechanisms have to be considered, in particular improved intrarenal hemodynamics.</jats:p>