Influence of growth factors on the proliferation of vascular smooth muscle cells isolated from subtotally nephrectomized rats after endothelin or angiotensin II antagonism

Abstract

Background. Cardiovascular disease is the most important cause of death in patients with end-stage renal disease. In uraemia, the renin-angiotensin-aldosterone and endothelin (ET) systems are activated. It is not known whether inhibition of these systems attenuates the proliferation of isolated smooth muscle cells of uraemic rats. Methods. Subtotally nephrectomized (SNX) rats were treated with an ETA receptor antagonist, an ETAB receptor antagonist, the angiotensin type 1 (AT1) receptor antagonist losartan (all 10mg/kg body weight/day) or the angiotensin-converting enzyme (ACE) inhibitor trandolapril (0.1 mg/kg body weight/day) or received no medication (SNX) for 12 weeks. Then, aortal smooth muscle cells (SMCs) were isolated and cultivated. After incubation of SMCs with different growth factors (5-7 days), proliferation was measured using a bromodeoxyuridine enzyme-linked immunosorbent assay (BrdU ELISA). Results. Higher maximum levels of proliferation were found in SMCs from untreated SNX rats than in SMCs from control animals [platelet-derived growth factor-BB (PDGF-BB) 486.60 ± 8.27 vs 346.74 ± 4.60%, basic fibroblast growth factor (bFGF) 176.68 ± 6.50 vs 123.71 ± 1.49%, tumour necrosis factor-α (TNF-α) 153.38 ± 10.16 vs 122.27 ± 1.41%]. Treatment with ET receptor antagonists or losartan attenuated growth factor-stimulated proliferation (PDGF-BB: ETA receptor antagonist, 135.71 ± 1.08%; ETAB receptor antagonist, 122.72 ± 0.58%; losartan: 103.69 ± 1.83%, n=8). SMCs from trandolapril-treated rats showed an increased response (PDGF-BB 663.48 ± 7.00%, n=8). Conclusions. Treatment of SNX rats with ET receptor antagonists or losartan reduced growth factor-induced SMC proliferation in vitro. However, further investigations with uraemic patients have to clarify whether angiotensin or ET receptor antagonists inhibit the development of atherosclerosis. © ERA-EDTA 2004; all rights reserved.