Effects of benidipine hydrochloride on autonomic nervous activity in hypertensive patients with high- and low-salt diets

The effects of benidipine hydrochloride (CAS 91559-74-5, Coniel®) on autonomic nervous activity in hypertensive patients with high- and low-salt diets were investigated. Six patients having a urinary sodium excretion of 80 mEq/day or less (low salt group) and 6 patients having a urinary sodium excretion of 200 mEq/ day or more (high salt group) were orally given benidipine hydrochloride (4 mg). Before and four weeks after the treatment with benidipine, 24-h circadian variation in blood pressure and 24-h Holter electrocardiogram (ECG) were recorded. The low frequency power spectrum of heart rate (LF power; 0.04−0.15 Hz), high frequency power spectrum of heart rate (HF power; 0.15−0.40 Hz), and the ratio of LF to HF (LF/HF) were calculated, and these parameters were averaged every hour in every subject. HF power was significantly lower and LF/HF ratio was significantly higher in the highsalt group than in the low-salt group before the treatment. However, the benidipine treatment significantly increased the HF power in both groups, particularly in the high-salt group, and significantly decreased the LF/HF ratio in both groups. Moreover, there was no significant difference in the antihypertensive effect of benidipine between the high- and low-salt intake groups. These results suggest that benidipine favourably influences blood pressure and autonomic nervous activity in hypertensive patients with a high-salt intake. It is concluded that benidipine may be useful for improving the development of salt-induced hypertension and its accompanying haemodynamic responses.