Ca2+ channels of the L-type in peripheral blood lymphocytes of essential hypertensives

Abstract Ca 2 + channels of the L-type were assayed in human peripheral blood lymphocytes of normotensive control subjects and of essential hypertensives using radioligand binding assay techniques. The dihydropyridine Ca 2 + channel blocker [ 3 H]( + )-PN 200-110 [isopropyl1-4-(2,1,3-benzoxadiazol-4-yl)1,4-dihydro-5-methoxycarbonyl-2,6-dimethyl-3-pyridine carboxylate] was used as a ligand. [ 3 H]( + )-PN 200 110 was bound specifically to human peripheral blood lymphocytes in a manner consistent with the labeling of Ca 2 + channels of the L-type. No significant differences in the dissociation constant (K d ), in the maximum density of binding sites (B max ) or in the pharmacological profile of [ 3 H]( + )-PN 200 110 binding were found between normotensive subjects and different degree essential hypertensives. Analysis of the intralymphocytic free Ca 2 + concentration did not reveal differences between normotensive subjects and essential hypertensives. Although hypertension is associated with altered membrane handling of Ca 2 + , no changes in the expression of peripheral blood lymphocyte Ca 2 + channels of the L-type or in intralymphocytic Ca 2 + concentrations were found in essential hypertensives. Human peripheral blood lymphocytes therefore cannot represent a peripheral marker of altered Ca 2 + handling in hypertension.