Objective: Both LDL-cholesterol and angiotensin II have been shown to increase the risk for and severity of cardiovascular disease. In hypercholesterolaemia, experimental studies have demonstrated an increased angiotensin type 1 (AT1) receptor expression on vascular smooth muscle cells and an increased vascular responsiveness to vasopressors has been documented in humans. We investigated in a normocholesterolaemic young population whether vascular responsiveness to angiotensin II (Ang II) infusion depends on LDL-cholesterol serum levels in the systemic and renal circulation.
Design and methods: Changes in systolic and diastolic blood pressure (deltaBP) to Ang II infusion (0.5 and 3.0 ng/kg per min) were investigated in 103 normocholesterolaemic (LDL-cholesterol < 160 mg/dl) young white men (26+/-3 years; 24 h BP: 128+/-10/75+/-7 mmHg) without cardiovascular disease. According to their LDL-cholesterol levels, participants were classified into tertiles (lower tertile < 85 mg/dl, middle tertile 85-111 mg/dl, upper tertile > 111 mg/dl).
Results: Blood pressure (BP) responses to Ang II infusion 3.0 ng/kg per min were enhanced in the group with the highest LDL-cholesterol levels (delta systolic BP: +12.8+/-6.7, +13.2+/-8.6, +17.9+/-9.6, P < 0.02; delta diastolic BP: +11.1+/-5.8, +11.5+/-6.5, +16.5+/-8.3, P < 0.01, for the lower, middle and upper tertiles, respectively). This holds true when baseline BP was taken into account as a confounding covariable (P < 0.015). BP responses to Ang II infusion were related to LDL-cholesterol serum levels (delta systolic BP: r = 0.26, P = 0.01; delta diastolic BP: r = 0.32, P = 0.001). In multiple stepwise regression analysis, LDL-cholesterol emerged as the strongest determinant of vascular responsiveness to Ang II (delta systolic BP: P < 0.01; delta diastolic BP: P < 0.001).
Conclusion: In young male subjects, responsiveness to Ang II is determined by the LDL-cholesterol serum level even in the normal range of LDL-cholesterol, thereby potentially contributing to the cardiovascular risk of LDL-cholesterol even within the so-called normal range.