Intracellular calcium in hypertension: effect of treatment with beta-adrenoreceptor blockers.

In 41 essential hypertensive patients, the intraerythrocytic free calcium (aiCa2+) was determined before and after oral treatment with beta-adrenoreceptor blockers (atenolol, metipranolol, and pindolol). The measurements were performed by means of an ion-selective electrode. During the 4 weeks of treatment, the aiCa2+ decreased from 7.4 +/- 2.3 (mean +/- SD) to 4.1 +/- 1.7 mumol/l (p less than 0.001) in the total group of 41 patients. In the patients treated with atenolol (n,15), the aiCa2+ decreased from 7.1 +/- 1.8 to 4.4 +/- 1.7 mumol/l (p less than 0.001); in those treated with metipranolol (n,13), aiCa2+ decreased from 7.4 +/- 2.7 to 4.3 +/- 2.0 mumol/l (p less than 0.001); and in those treated with pindolol (n,13), aiCa2+ decreased from 7.6 +/- 2.4 to 3.8 +/- 1.5 mumol/l (p less than 0.001). In the total group, the mean reduction of the mean blood pressure was 12 mm Hg. In the atenolol subgroup, the blood pressure was reduced by 11 mm Hg, in the metipranolol subgroup by 15 mm Hg, and in the pindolol subgroup by 18 mm Hg. Thus, the reduction of the blood pressure during beta-adrenoreceptor blockade is accompanied by a reduction of the free calcium of the red cells. The calcium lowering effect as the antihypertensive potency is roughly equal among the different beta-adrenoreceptor blockers.