Cilnidipine but not amlodipine suppresses sympathetic activation elicited by isometric exercise in hypertensive patients.

Pupillometry was used to evaluate the effects of the calcium channel blockers cilnidipine (CL) and amlodipine (AM) on changes in autonomic nervous activity induced by isometric exercise in patients with hypertension. After handgrip exercise, the velocity of miosis increased in both the CL and AM groups. However, the velocity of mydriasis increased in only the AM group. Velocity slopes of miosis and mydriasis were smaller in the CL group than in the AM group. The low-to-high frequency ratio obtained from pulse wave analysis increased in only the AM group. Sympathetic activation elicited by isometric exercise was suppressed more effectively by CL than by AM.

Taurine suppresses pressor response through the inhibition of sympathetic nerve activity and the improvement in baro-reflex sensitivity of spontaneously hypertensive rats.

To investigate the effect of taurine on the sympathetic nervous system, I observed pressor responses of perfused mesenteric arteries by electrical stimulation and baro-reflex sensitivity of spontaneously hypertensive rats (SHR/Izm) and control Wistar-Kyoto rats (WKY/Izm) treated with taurine. Taurine added to the perfusate suppressed norepinephrine (NE) overflow and the pressor response mediated by electrical stimulation of isolated perfused mesenteric arteries. Taurine showed a greater suppressive effect on NE overflow and the pressor response mediated by electrical stimulation in SHR/Izm rats than in WKY/Izm rats. Increment of renal sympathetic nerve activity induced by jet-air stress was suppressed in SHR/Izm rats treated with 3% taurine. The arterial baro-reflex sensitivity was more sensitive in SHR/Izm rats treated with taurine than in those exposed to no taurine. These data suggest that taurine lowers blood pressure directly via the suppression of NE release from the peripheral sympathetic nerve and the improvement of impaired baro-reflex sensitivity.

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.