Abnormal platelet Ca²⁺handling accompanied by increased cytosolic free Mg²⁺in essential hypertension

Abstract

platelets; mag-fura 2; fura 2 IN THE LAST SEVERAL DECADES, abnormal Ca 2ϩ handling in many cell types from human subjects and animal models of primary hypertension has been reported and proposed as a factor in the pathogenesis of hypertension. Platelets are often used in the study of cellular cation metabolism in hypertension, because they are readily available for study and are thought to share a number of features with vascular smooth muscle cells (20). Most investigators have reported that basal levels of cytosolic free Ca 2ϩ concentration ([Ca 2ϩ ] i ) are higher in human subjects with essential hypertension than in normotensive subjects (5,8,11,16,30) MATERIALS AND METHOD Subjects.We studied 30 patients with essential hypertension (15 men, 15 women, mean age 51 Ϯ 11 yr) and 30 sex-and age-matched normotensive controls (15 men, 15 women, mean age 50 Ϯ 13 yr). Normotensive controls were recruited from healthy subjects who underwent annual physical examinations. Hypertension was defined as systolic blood pressure Ն160 mmHg and/or diastolic blood pressure Ն95 mmHg on each of three consecutive clinical visits. We measured blood pressure with a mercury sphygmomanometer in sitting subjects at least five times during each clinical visit and used the average value of these measurements. The blood pressure in normotensives was consistently Ͻ140/90 mmHg. None of the hypertensives or normotensives had received any medication for at least 4 wk before the study. Subjects with secondary forms of hypertension were excluded by careful clinical examination. Hypertensive patients and normotensive controls were maintained on a regular diet with an intake of 170 mmol/day NaCl to allow stabilization of the systemic Na ϩ balance, and they ingested constant amounts of K ϩ (2,000 mg/day), Ca 2ϩ (500 mg/day), and calories (40 kcal/kg) for 7 days before the study. Venous blood was collected from fasting and resting subjects, slowly and steadily via a 19-gauge needle into a syringe containing 3.8% trisodium citrate (1:9 by vol, total 30 ml), using a two-syringe method (21)

Abnormal magnesium status in patients with cardiovascular diseases

“…In the present study, in Japanese individuals, the concentrations of serum total and ionized Mg were unchanged, and the intra-erythrocyte Mg concentration was increased, in essential hypertension. This finding is consistent with our previous report of an increase in the intraplatelet concentration of free Mg in patients with essential hypertension [35], and with findings in spontaneously hypertensive rats [36]. In these human subjects and in the rats with genetic hypertension, the intracellular Ca# + level was increased in the resting state and in stimulated conditions [37,38].…”

Surface Modifications of Magnesium Alloys for Biomedical Applications

“…It is a novel anodic oxidation technique to deposit ceramic coatings on the surface of metals, such as Al, Ti, Mg, Ta, W, Zn, and Zr and their alloys. 22,30 During MAO processes, the anode made by metals is immersed in an aqueous solution, and an asymmetric alternating voltage is applied between the anode and the cathode. MAO processes are typically characterized by the phenomenon of electrical discharge on the anode.…”

Effects of Dairy Products on Intracellular Calcium and Blood Pressure in Adults with Essential Hypertension

“…Resnick and others [15,16] have proposed that hypertension and associated disorders result from elevated (Ca) i concentrations and reciprocally suppressed intracellular magnesium levels. Hypertension is associated with significantly higher intracellular calcium and sodium concentrations [17][18][19][20] and lower intracellular magnesium levels [21][22][23]. A direct correlation between BP and (Ca) i levels has been shown in a variety of cell types [17,19,24].…”