Background— The present studies were undertaken to investigate the potential effect of a hydroxymethylglutaryl coenzyme A reductase inhibitor (statin) to enhance the inhibitory effect of an angiotensin (Ang) II type 1 (AT₁) receptor blocker (ARB) on vascular neointimal formation and to explore the cellular mechanism of cross-talk of the AT₁ receptor and statin in vascular smooth muscle cells (VSMCs).

Methods and Results— Neointimal formation and the proliferation of VSMCs induced by cuff placement around the femoral artery were significantly inhibited by treatment with an ARB, valsartan, at a dose of 0.1 mg · kg⁻¹ · d⁻¹ and with fluvastatin at a dose of 1 mg · kg⁻¹ · d⁻¹, which did not influence mean arterial blood pressure or plasma cholesterol level, whereas valsartan or fluvastatin alone at these doses did not affect neointimal formation or the proliferation of VSMCs. Pretreatment with fluvastatin (≈5 μmol/L) for 24 hours significantly inhibited Ang II (1 μmol/L)–mediated DNA synthesis and c-fos promoter activity in cultured VSMCs. Moreover, pretreatment of VSMCs with fluvastatin significantly inhibited Ang II–mediated extracellular signal-regulated kinase (ERK) activation and tyrosine- and serine-phosphorylation of signal transducer and activator of transcription (STAT)1 and STAT3. AT₁ receptor–mediated recruitment of Rac-1 to Janus kinase (Jak) family/STATs was also inhibited by fluvastatin. Consistent with these in vitro results, phosphorylation of ERK, STAT1, and STAT3 was attenuated by the coadministration of valsartan and fluvastatin even at low doses in vivo.

Conclusion— These results suggest that the cholesterol-independent inhibition of AT₁ receptor–mediated VSMC proliferation by statins may contribute to the beneficial effects of statins combined with an ARB on vascular diseases.