Trilostane - a new and effective drug for primary aldosteronism

in The adrenal gland and hypertension (1985)

Human red blood cells--an ideal model system for the action of calcium agonists and antagonists.

in Journal of Hypertension. Supplement) (1984), 2(3), 577-80

To characterize the pharmacological properties of the slow calcium channel of human red blood cells, we studied the action of various calcium antagonists and two agonists on the 45Ca2+-influx. The Ca2 ... [more ▼]

To characterize the pharmacological properties of the slow calcium channel of human red blood cells, we studied the action of various calcium antagonists and two agonists on the 45Ca2+-influx. The Ca2+-ejecting ATPase was inhibited by vanadate. All dihydropyridine derivatives tested showed their inhibiting or stimulating effect on the channel at concentrations attainable in vivo (nitrendipine:Ki = 2.5; Bayer K 6244:Ki 5 microM; nicardipine:Ki = 15 microM, Ks = 0.5 microM; Ciba 28 392:Ki = 20, Ks = 0.3 microM; Ki = inhibition constant, Ks = stimulation constant). Of special interest was the biphasic behaviour (stimulation and inhibition) of the calcium antagonist nicardipine and the agonist Ciba 28 392. The maximum inhibition by the phenylalkylamine derivative verapamil was obtained at much higher concentrations (250 microM; Ki = 100). These data suggest that the calcium channel of human red blood cells has pharmacological properties very similar to the channel in heart and smooth muscle cells with respect to dihydropyridine action. Therefore, human red blood cells are an ideal model to study the action of calcium agonists and antagonists. [less ▲]

Altered calcium and sodium metabolism in red blood cells of hypertensive man: assessment by ion-selective electrodes.

in Journal of hypertension (1983), 1(2), 171-6

Free intracellular calcium [Ca2+]i, sodium [Na+]i and potassium [K+]i were assessed in freeze-thawed human red blood cells (RBC) by ion-selective electrodes. After metabolic depletion by 30 mM 2-desoxy ... [more ▼]

Free intracellular calcium [Ca2+]i, sodium [Na+]i and potassium [K+]i were assessed in freeze-thawed human red blood cells (RBC) by ion-selective electrodes. After metabolic depletion by 30 mM 2-desoxy-glucose, [Ca2+]i increased faster and to significantly higher values in RBC from 16 patients with mild to moderate essential hypertension (mean diastolic blood pressure 111 +/- 10 mmHg) than in the RBC of 24 normotensives. The rate of [Ca2+]i increase was 7.0 +/- 3.6 versus 3.7 +/- 4.0 mumol/h/l cells (P less than 0.01) for the first 24 h and 8.1 +/- 4.8 versus 6.4 +/- 3.5 mumol/h/l cells for the following 24 h. [Na+]i before and after 24 h incubation was significantly higher in hypertensives, whereas basal [Ca2+]i and [K+]i before and after incubation were the same in both groups. After Ca loading by ionophore A 23187, the maximum rate of [Ca2+]i extrusion was not significantly lower in intact RBC from hypertensives than in those from normotensives (59.5 +/- 7.8 versus 87.9 +/- 18.1 mumol/min/l cells). These results indicate disturbances in RBC Ca metabolism similar to those observed earlier for Na and K. If generalized, the defect could lead to raised [Ca2+]i in smooth muscle and sympathetic nerve tissue, thus causing increased vascular tone and probably catecholamine release with subsequent arterial hypertension. [less ▲]