Pathophysiology of unilateral ureteral obstruction: studies from Charlottesville to New York

More than 30 years ago the decreased renal blood flow and glomerular filtration rate characteristic of unilateral ureteral obstruction (UUO) was described. In the ensuing time, much has been learned about the involvement of nitric oxide (NO) and transforming growth factor-beta (TGF-beta) in the pathophysiology of UUO.

We measured renal blood flow and glomerular filtration rate in dogs and rats, and assessed the effect of altering the availability of NO on these parameters. In rats and mice we used an antibody to TGF-beta, NO synthase gene deletion and inducible nitric oxide synthase gene therapy to assess the role of TGF-beta and NO in renal fibrosis.

Results of our studies suggest 2 strategies that have the potential to be incorporated into clinical trials. The first would be replenishment of the NO system with arginine (or a NO donor) to decrease renovascular resistance and increase renal nitric oxide. Either in addition to the first strategy or separately, interstitial fibrosis could be targeted. Strategies for inhibiting fibrosis include antibody to TGF-beta, use of antisense oligonucleotides to TGF-beta, use of drugs that inhibit other pro-fibrotic mediators or gene therapy to inhibit fibrosis.

While these studies have primarily centered on acute UUO, the findings in this model of renal injury may potentially be transferable to other entities that are characterized by decreased renal function and increased renal fibrosis such as different forms of interstitial nephropathy or diabetic glomerulopathy.