Effects of Chronic Renal Failure on Caveolin-1, Guanylate Cyclase and AKT Protein Expression

Chronic renal failure (CRF) has been documented to cause oxidative stress and alter nitric oxide (NO) metabolism. However, the effect of CRF on proteins related to NO bioactivity has not been investigated. The present study was designed to test the hypothesis that CRF would induce changes in caveolin-1 (Cav-1), soluble guanylate cyclase (sGC) and Akt, three proteins important in regulating NO synthase (NOS) functionality. Male Sprague-Dawley rats were randomized to CRF via 5/6 nephrectomy or sham-operated control groups. After 6 weeks, body weight, blood pressure, creatinine clearance, plasma creatinine, urinary cyclic guanosine monophosphate (cGMP) and immunodetectable levels of Cav-1, sGC and Akt were determined in the renal, aorta, heart and liver tissues from both groups. CRF resulted in marked decreases in body weight and creatinine clearance, and elevation of blood pressure and plasma creatinine. An apparent upregulation of sGC protein abundance in renal tissue was noted, with no change in aorta, heart and liver. This was accompanied by a reduction in urinary cGMP levels, indicative of sGC dysfunction. Cav-1 protein abundance was increased in aortic, liver and renal tissues. In contrast, CRF depressed Akt abundance in aorta, heart and liver tissues. These data document that CRF is characterized by alteration in the abundance of proteins regulating NO function in hepatic, vascular, cardiac and renal tissues, and a decrease in cGMP, which contributes to hypertension and changes in NO bioactivity previously noted in this model.