Effect of an angiotensin receptor antagonist, TCV-116, on sympathetic nerve activity in patients with essential hypertension.

: The effects of an angiotensin II receptor (AT1) antagonist on sympathetic nervous responses to a mental arithmetic task and a cold pressor test were investigated using a placebo-controlled, single-blind design in 8 patients with essential hypertension (53 +/- 3 years). All patients received a placebo for 2 weeks (placebo run-in period), after which the control group (P; n = 4) continued to receive the placebo, while the experimental group (TCV; n = 4) received TCV-116 at 4 mg/day for 4 weeks (treatment period). After basal measurements were carried out, an arithmetic task and a cold pressor test were conducted on the last day of each period. Blood pressure (BP), heart rate (HR) and electrocardiogram (ECG) were continuously monitored. Muscle sympathetic nerve activity (MSNA) was assessed by determining the burst rate of the mean voltage neurogram obtained from the tibial nerve. Sympathovagal balance was also assessed, by determining the area ratio of the low frequency (LF: 0.05-0.15 Hz) to high frequency bands (HF: 0.16-0.5 Hz) of a power spectral analysis of HR variability (maximum entropy method). During the placebo run-in period, there were no significant differences in basal BP, HR, LF/HF or MSNA between the two groups. During the treatment period, basal mean BP in the TCV group was significantly lower (p < 0.05) than that in the P group, but there were no significant differences in basal HR, LF/HF or MSNA between the two groups. Although the arithmetic stress significantly increased BP, HR and LF/HF in both groups, MSNA was not significantly altered in either group.(ABSTRACT TRUNCATED AT 250 WORDS)