Hormones – Cytokines – Signaling
Kidney International (2001) 59, 1290–1303; doi:10.1046/j.1523-1755.2001.0590041290.x
Role of nitric oxide in renal tubular apoptosis of unilateral ureteral obstruction
Akira Miyajima, Jie Chen, Dix P Poppas, E Darracott Vaughan Jr and Diane Felsen
Center for Pediatric Urology and Laboratory for Minimally Invasive Urologic Surgery, Department of Urology, New York Presbyterian Hospital, Weill Medical College of Cornell University, New York, New York, USA
Correspondence: Diane Felsen, Ph.D., Department of Urology, Weill Medical College of Cornell University, Box 94, 1300 York Avenue, New York, New York 10021, USA. E-mail: dfelsen@med.cornell.edu
Received 16 August 1999; Revised 27 September 2000; Accepted 30 October 2000.
Abstract
Role of nitric oxide in renal tubular apoptosis of unilateral ureteral obstruction.
Background
The obstructed kidney in unilateral ureteral obstruction (UUO) is characterized by renal atrophy and tissue loss, which is mediated by renal tubular apoptosis. We sought to determine whether NO is involved in renal tubular apoptosis in vitro and in vivo.
Methods
Rat renal tubular epithelial cells (NRK-52E) were subjected to mechanical stretch, and apoptosis and cell size were analyzed by flow cytometry. Furthermore, we studied UUO in mice lacking the gene for inducible nitric oxide synthase (iNOS-/-) and their wild-type littermates. Tubular apoptosis and proliferation were detected by immunostaining. NOS activity and NOS expression were assessed by a citrulline assay and Western blot, respectively.
Results
Stretching-induced apoptosis in NRK-52E, which was reduced when NO was increased; conversely, stretch-induced apoptosis was increased when a NOS inhibitor was added to the cells. Stretched cells are larger and more apoptotic than unstretched cells. In UUO, the obstructed kidney of iNOS-/- mice exhibited more apoptotic renal tubules than the wild-type mice through 14 days of UUO. The obstructed kidney of iNOS-/- mice at day 3 showed more proliferative tubules compared with wild type. The obstructed kidney of wild-type mice exhibited higher total NOS activity until day 7 after UUO compared with iNOS-/- mice. However, the obstructed kidney of day 14 wild-type mice exhibited significantly lower iNOS activity and protein compared with the day 0 kidney.
Conclusion
These results suggest that mechanical stretch is related to renal tubular apoptosis and that NO plays a protective role in this system in UUO.
Keywords:
cell death, stretching-induced apoptosis, renoprotection, obstructed kidney, hemodynamics
