The effect of angiotensin II and telmisartan on systemic arterial Impedance in rats

抄録

To design a lumped-parameter hemodynamic model that can respond to the renin-angiotensin system, the effects of angiotensin II and its blocker, telmisartan, on systemic arterial impedance (Z_AO) were examined in rats (n = 5). While carotid sinus pressure was fixed at 100 mmHg, mean aortic pressure (P_AO) was changed stepwise at 60, 80 and 100 mmHg every three minutes. Random left ventricular pacing was employed to determine high-resolution Z_AO during (1) baseline, (2) administration of angiotensin II, and (3) telmisartan. A three-element Windkessel model was used to quantify Z_AO (R₁: characteristic impedance, R₂: peripheral resistance, and C: aortic compliance). R₂ increased with P_AO in all three conditions, while R₁ remained relatively constant. Angiotensin II increased R₂ by 18.5% without affecting R₁. Telmisartan decreased R₂ by 20.0% without affecting R₁. These results suggest that R₂ should be modulated to reflect the effects of P_AO and the renin-angiotensin system.