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Correlation of platelet calcium with blood pressure. Effect of antihypertensive therapy
Insights
Elevated intracellular free calcium in blood platelets is linked to hypertension. Lowering calcium levels through medication correlates with reduced blood pressure, suggesting a key role for calcium in blood pressure regulation.
Area of Science:
- Cardiovascular Physiology
- Hypertension Pathophysiology
- Cellular Calcium Signaling
Background:
- Intracellular free calcium is crucial for vascular smooth muscle contraction.
- Abnormal calcium levels are implicated in essential hypertension.
- Blood platelets share cellular features with vascular smooth muscle cells.
Purpose of the Study:
- To investigate intracellular free calcium levels in blood platelets of hypertensive patients.
- To determine the correlation between platelet free calcium and blood pressure.
- To assess the effect of antihypertensive treatment on platelet free calcium.
Main Methods:
- Utilized an intracellularly trapped fluorescent dye to measure platelet free calcium concentration.
- Compared calcium levels in normotensive subjects, patients with borderline hypertension, and established essential hypertension.
- Analyzed correlations between free calcium levels, systolic, and diastolic blood pressure.
- Monitored changes in platelet free calcium following antihypertensive treatment.
Main Results:
- Platelet free calcium levels were significantly elevated in patients with borderline and essential hypertension compared to normotensive controls.
- A strong positive correlation was observed between platelet free calcium levels and both systolic and diastolic blood pressure (r=0.883 and r=0.931, respectively).
- Antihypertensive treatments (calcium-entry blockers, beta-blockers, diuretics) led to a reduction in platelet free calcium, which correlated with decreased blood pressure.
Conclusions:
- Elevated intracellular free calcium in platelets is associated with hypertension.
- Platelet free calcium levels may serve as a biomarker for blood pressure.
- The findings suggest that humoral or pharmacologic factors influencing blood pressure also affect intracellular calcium concentration.
Abstract:
Intracellular free calcium has been implicated in vascular smooth-muscle contraction and in the pathophysiology of essential hypertension. We studied free-calcium levels in blood platelets, which have many features in common with vascular smooth-muscle cells. With use of an intracellularly trapped fluorescent dye, the free-calcium concentration in platelets was found to be elevated in 9 patients with borderline hypertension and 45 patients with established essential hypertension, who were compared with 38 normotensive subjects. There was a close correlation between the free-calcium level and both systolic and diastolic blood pressure (n = 92; r = 0.883 for systolic pressure and 0.931 for diastolic pressure; P less than 0.001 for both). Antihypertensive treatment with calcium-entry blockers (n = 15), beta-adrenoceptor blockers (n = 12), or a diuretic (n = 6) resulted in a reduction in free calcium, and this correlated with the fall in blood pressure (P less than 0.001). The intracellular free-calcium concentration in platelets may be determined by the same humoral or pharmacologic factors that determine the height of blood pressure.