Effects of azelnidipine and amlodipine on exercise-induced sympathoexcitation assessed by pupillometry in hypertensive patients.

The pupil is a suitable end organ for studying autonomic function because both sympathetic and parasympathetic nerve activity can be evaluated independently using a light stimulus. Sympathetic response elicited by physical stress is augmented in hypertensive patients compared with normotensive subjects, which increases the risk of cardiovascular events. We used pupillometry to evaluate the effects of the calcium channel blockers azelnidipine (AZ) and amlodipine (AM) on changes in autonomic nervous activity induced by isometric exercise in patients with hypertension. Twenty patients with essential hypertension who were administered AM and 21 who were administered AZ underwent a pupillary function test and blood pressure (BP) and pulse rate (PR) measurements before and after isometric handgrip exercise (IHG). Maximal velocities of pupil constriction (VC) and re-dilation (VD) obtained with light stimulation for 1 s were used as indices of parasympathetic and sympathetic nerve activity, respectively. Increases in systolic BP and PR elicited by IHG were significantly smaller in the AZ group than in the AM group. After IHG, both VC and VD significantly increased in the AM group but not in the AZ group. The low-to-high frequency ratio obtained from analysis of PR variability, another measure of sympathetic activity, also increased in only the AM group. Thus AZ inhibited autonomic activation and suppressed cardiovascular responses to IHG more effectively than AM. The sympathoinhibitory effect of AZ may therefore be beneficial for patients with essential hypertension. In addition, pupillometry was shown to be a useful tool for assessing autonomic function in hypertensive patients.