Efficacy of an L- and N-type calcium channel blocker in hypertensive patients with neurovascular compression of the rostral ventrolateral medulla

The rostral ventrolateral medulla is an important regulation center of sympathetic nerve activity. Several clinical studies have indicated a possible association between essential hypertension and neurovascular compression of the rostral ventrolateral medulla. We have found that patients with essential hypertension and neurovascular compression of the rostral ventrolateral medulla by adjacent arteries have increased sympathetic nerve activity and that microvascular decompression of the rostral ventrolateral medulla normalizes blood pressure and sympathetic nerve activity. Although sympatholytic agents are expected to lower blood pressure in these patients, this remains to be clarified. In this study, we evaluated the effect of cilnidipine, a calcium channel blocker that blocks both vascular L-type and sympathetic N-type Ca2+ channels in hypertensive patients with neurovascular compression. Using high-resolution magnetic resonance imaging, 46 patients with untreated essential hypertension were distributed into those with and without neurovascular compression of the rostral ventrolateral medulla. All patients were prescribed 10 mg of cilnidipine for 16 weeks. Office and home blood pressure, plasma norepinephrine and left ventricular mass index were measured by echocardiography before and after cilnidipine treatment, and changes were compared between the two groups. At baseline, plasma norepinephrine was significantly higher in patients with neurovascular compression. Decreases in office and home blood pressure, plasma norepinephrine and left ventricular mass index were significantly greater in patients with neurovascular compression. These results suggest that cilnidipine lowers blood pressure by inhibiting enhanced sympathetic nerve activity and reduces left ventricular mass in hypertensive patients with neurovascular compression of the rostral ventrolateral medulla. Hypertension Research ( 2009) 32, 700-705; doi:10.1038/hr.2009.80; published online 12 June 2009