Erythrocyte membrane calcium binding in normotensive and hypertensive subjects.

Calcium binding to erythrocyte membranes has been determined in patients with essential hypertension (EHT) and normotensive subjects with (NT + FH) and without (NT - FH) a family history of hypertension, to investigate its relationship to high blood pressure. The calcium content of erythrocyte membranes was measured by atomic absorption spectrophotometry after incubation in 0 (basal) or 40 mmol/l (maximal binding) calcium chloride. Basal calcium binding was reduced to a similar extent in both EHT and NT + FH subjects (11.4 +/- 0.5 and 10.9 +/- 0.9 mumol/g protein versus 13.7 +/- 0.6 mumol/g protein in NT - FH, P less than 0.01 for both). Maximal binding showed a similar pattern. These data suggest that cell membrane calcium binding is not directly related to blood pressure elevation but is the result of an inherited cell membrane defect which is present in essential hypertension patients and their relatives and which affects several membrane functions.