Abstract 3618: Aldosterone Blocking Effect of L-type Calcium Channel Blockers
Introduction: L-type calcium channel blocker (CCB) is widely used for the treatment of hypertension. Aldosterone blocker has organ protective effects. To evaluate whether CCB has an aldosterone blocking effect, we checked binding inhibition of CCB to mineral corticoid receptor (MR) in vitro experiment, and measured serum potassium (K) level before and after the treatment of hypertensive patients with CCB.
Methods: In vitro study, binding assay was performed using human MR expression cells with nicardipine or amlodipine, dihyrdopiridine (DP) CCBs or diltiazem, a benzodiazepine (BZ) CCBs. Twenty-six patients with essential hypertension were studied. Patients with renal failure were excluded in the present study. They were divided into two groups: group N (n=13), intravenous infusion of nicardipine (n=13, 2 to 10 mg/kg/min), and group D (n=13), intravenous infusion of diltiazem (5 to 15 mg/kg/min). We measured serum K level before and after the treatment of nicardipine and diltiazem in these patients. We also measured serum K in 13 hypertensive patients before and two weeks after the treatment with oral administration of amlodipine (5 mg/day), a DP CCB.
Results: Nicardipine has a high affinity (Ki=8.82 nM) for human MR although diltiazem (100 mcM) (inhibition (%): 0.8 +/− 4.3) and amlodipine (100 mcM) (inhibition (%): 22.1 ±4.5) did not. Nicardipine treatment significantly increased serum K level (3.9 +/−0.4 mEq/l to 4.5 +/− 0.5, p<0.0001) although amlodiline (K; 4.1 +/− 0.2 to 4.1 +/− 0.2) and diltiazem treatment did not (K; 4.1 +/− 0.3 to 4.1 +/− 0.3). Urine K/Na ratio was significantly decreased after nicardipine treatment (0.89 +/− 0.15 to 0.32 +/− 0.10).
Conclusion: Nicardipine has an aldosterone blocking effect, and it may be beneficial for organ protection as well as blood pressure lowering in hypertensive patients.