Effect of Angiotensin II Receptor Antagonism on Cerebral Vasomotor Reserve in Humans

Angiotensin II receptor antagonists have been reported to modulate cerebrovascular flow in animals. We applied frequency-domain techniques to explore whether angiotensin II receptor activity plays a role in cerebrovascular dynamics in humans. Essential hypertensive patients with (AIIA, n = 10) and without (HT, n = 10) an angiotensin II receptor antagonist (Volsartane) and healthy with matched (CON, n = 10) and younger (YOUNG, n = 10) ages were enrolled. They underwent measurement of middle cerebral artery flow velocity (MCAFV) by transcranial Doppler ultrasound and non-invasive beat-to-beat arterial blood pressure (ABP). Fluctuations in ABP and MCAFV were diffracted into high-frequency (HF, 0.15-0.4 Hz), low-frequency (LF, 0.04-0.15 Hz), and very low-frequency (VLF, 0.016-0.04 Hz) components. The mean age did not statistically significantly differ among the CON, HT, and AIIA groups. HT had significantly higher mean ABP, lower LF fluctuations of ABP and MCAFV, but similar ABP-MCAFV transfer magnitude compared with CON. HF transfer magnitude of AIIA was significantly higher than those of HT and CON, but similar to that of YOUNG. We conclude that the elderly with chronic essential hypertension has a suppressive effect on cerebral vasomotor reserve, in which angiotensin II receptor activity may play an active role.