Effect of nifedipine on blood pressure and on intracellular calcium in arterial hypertension.

In 13 patients with essential and renal hypertension, the influence of nifedipine on the intracellular free Ca2+ concentration was tested. Measurements of free Ca2+ were performed with a Ca2+ -selective electrode. The patients were additionally treated with a conventional antihypertensive combination therapy, by which the blood pressure could not be lowered satisfactorily. Under treatment with 30-60 mg of nifedipine daily, blood pressure was lowered from 192 +/- 23/95 +/- 15 mm Hg to 147 +/- 20/83 +/- 16 mm Hg. The intracellular Ca2+ activity fell from 7,115 +/- 14,139 to 1,886 +/- 3,748 mumol/L (p less than 0.05). The decrease in intracellular Ca2+ correlated very well with the initial value of Ca2+ activity (r = 0.966); furthermore, a relationship was found with the serum creatinine level (r = 0.48). On the other hand, there was no correlation with the decrease in blood pressure. In the lower dose range, nifedipine did not elicit a clear reduction in intracellular Ca2+. The results show that intracellular Ca2+ activity can be influenced by Ca2+ antagonists, but that there is no direct relationship between intracellular free calcium and blood pressure.