Correlation of platelet calcium with blood pressure. Effect of antihypertensive therapy.
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.
D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000032:analysis*; D001794:Blood Pressure / Q000187:drug effects*; D002118:Calcium / Q000097:blood*; D002121:Calcium Channel Blockers / Q000494:pharmacology / Q000627:therapeutic use; D004232:Diuretics / Q000494:pharmacology / Q000627:therapeutic use; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D013223:Statistics as Topic
D000319:Adrenergic beta-Antagonists; D002121:Calcium Channel Blockers; D004232:Diuretics; D002118:Calcium