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Erythrocyte membrane calcium binding in normotensive and hypertensive subjects
Insights
Reduced erythrocyte membrane calcium binding is linked to an inherited defect, not directly to high blood pressure. This defect is found in essential hypertension patients and their relatives, impacting cell membrane functions.
Area of Science:
- Cardiovascular Physiology
- Cell Membrane Biology
- Genetics of Hypertension
Background:
- Essential hypertension (EHT) is a complex cardiovascular disease.
- Erythrocyte membrane calcium binding is a potential biomarker for hypertension.
- Genetic predisposition plays a role in hypertension development.
Purpose of the Study:
- To investigate the relationship between erythrocyte membrane calcium binding and blood pressure.
- To determine if reduced calcium binding is a cause or consequence of essential hypertension.
- To explore the heritability of erythrocyte membrane calcium binding defects.
Main Methods:
- Atomic absorption spectrophotometry was used to quantify erythrocyte membrane calcium content.
- Calcium binding was measured under basal and maximal conditions (0 and 40 mmol/l CaCl2).
- Subjects included patients with essential hypertension (EHT) and normotensive individuals with (NT + FH) and without (NT - FH) a family history of hypertension.
Main Results:
- Basal calcium binding was significantly reduced in EHT and NT + FH subjects compared to NT - FH subjects.
- Maximal calcium binding followed a similar pattern, showing reduced binding in hypertensive and at-risk normotensive individuals.
- These findings indicate a consistent alteration in calcium handling by erythrocyte membranes in individuals with a predisposition to or presence of hypertension.
Conclusions:
- Reduced erythrocyte membrane calcium binding is not directly caused by elevated blood pressure.
- An inherited cell membrane defect, affecting calcium binding, is associated with essential hypertension and its familial aggregation.
- This inherited defect likely impacts multiple erythrocyte membrane functions.
Abstract:
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.