The renin-angiotensin system is critically involved in the pathogenesis of atherosclerosis. Cholesterol increases vascular responsiveness to angiotensin II by upregulation of the angiotensin 11 type 1 receptor. However, the effects of C-reactive protein (CRP) on vascular responsiveness to angiotensin 11 are unknown. We evaluated, in vitro, the vascular responsiveness of the internal thoracic artery to angiotensin 11 in patients who underwent coronary bypass grafting. We observed that increased preoperative CRP and increased cholesterol levels were strongly related to increased vascular responsiveness to angiotensin 11 (p <0.001 for the 2 comparisons). However, angiotensin II-mediated contraction was increased only when levels of CRP and cholesterol were jointly increased. In conclusion, our results suggest that CRP and cholesterol act synergistically on vascular responsiveness to angiotensin II. (c) 2006 Elsevier Inc. All rights reserved.