Rosiglitazone improves aortic arginine transport, through inhibition of PKCα, in uremic rats

Peroxisome proliferator-activated receptor (PPAR) agonists were shown to inhibit atherosclerosis through augmentation of endothelial nitric oxide synthase (eNOS) activity. In addition, rosiglitazone exerts a beneficial effect in chronic renal failure (CRF). Since l-arginine transport by CAT-1 (the specific arginine transporter for eNOS) is inhibited in uremia, we aimed to explore the effect of rosiglitazone on arginine transport in CRF. Arginine uptake by aortic rings was studied in control animals, rats, 6 wk following 5/6 nephrectomy (CRF) and rats with CRF treated with rosiglitazone. The decrease of arginine transport in CRF was prevented by rosiglitazone. Immunobloting revealed that CAT-1 protein was decreased in CRF but remained unchanged following rosiglitazone administration. Protein content of the membrane fraction of PKCα and phosphorylated CAT-1 increased significantly in CRF, effects that were prevented by rosiglitazone. PKCα phosphorylation was unchanged but significantly attenuated by rosigli...