Age is the main clinical determinant of large artery stiffness. Central arteries stiffen progressively with age, whereas peripheral muscular arteries change little with age. A number of clinical studies have analyzed the effects of age on aortic stiffness. Increase of central artery stiffness with age is responsible for earlier wave reflections and changes in pressure wave contours. The stiffening of aorta and other central arteries is a potential risk factor for increased cardiovascular morbidity and mortality. Arterial stiffening with aging is accompanied by an elevation in systolic blood pressure (BP) and pulse pressure (PP). Although arterial stiffening with age is a common situation, it has now been confirmed that older subjects with increased arterial stiffness and elevated PP have higher cardiovascular morbidity and mortality. Increase in aortic stiffness with age occurs gradually and continuously, similarly for men and women. Cross-sectional studies have shown that aortic and carotid stiffness (evaluated by the pulse wave velocity) increase with age by approximately 10% to 15% during a period of 10 years. Women always have 5% to 10% lower stiffness than men of the same age. Although large artery stiffness increases with age independently of the presence of cardiovascular risk factors or other associated conditions, the extent of this increase may depend on several environmental or genetic factors. Hypertension may increase arterial stiffness, especially in older subjects. Among other cardiovascular risk factors, diabetes type 1 and 2 accelerates arterial stiffness, whereas the role of dyslipidemia and tobacco smoking is unclear. Arterial stiffness is also present in several cardiovascular and renal diseases. Patients with heart failure, end stage renal disease, and those with atherosclerotic lesions often develop central artery stiffness. Decreased carotid distensibility, increased arterial thickness, and presence of calcifications and plaques often coexist in the same subject. However, relationships between these three alterations of the arterial wall remain to be explored.
Intracellular levels of free Mg2+ in human erythrocytes were determined by 31p NMR spectroscopy in 26 fasted subjects and were correlated with blood pressures and serum levels of total magnesium (bound and free Mg2+) and ionized calcium from the same subjects in a seated position. Untreated hypertensive individuals consistently demonstrated lower levels of intracellular free magnesium (192 ± 8 AM, n = 11) than either normotensive (261 ± 9.8 MM, n = 7, P < 0.001 vs. untreated hypertensive subjects) or hypertensive subjects whose blood pressure had been normalized on therapy (237 ±
Long-term dietary interventions induced significant weight loss and improved cardiovascular risk in high-risk patients. The prepared meal plan simultaneously provided the simplicity and nutrient composition necessary to maintain long-term compliance and to reduce cardiovascular risk.
To investigate alterations of magnesium metabolism in Type 2 (non-insulin-dependent) diabetes mellitus, we utilized a new magnesium-specific selective ion electrode apparatus to measure serum ionized magnesium (Mg-io) in fasting subjects with and without Type 2 diabetes, and compared these values to levels of serum total magnesium, and of intracellular free magnesium (Mgi) analysed by 31P-NMR spectroscopy. Both Mg-io (0.630 +/- 0.008 vs 0.552 +/- 0.008 mmol/l, p < 0.001) and Mgi (223.3 +/- 8.3 vs 184 +/- 13.7 mmol/l, p < 0.001), but not serum total magnesium, were significantly reduced in Type 2 diabetes compared with non-diabetic control subjects. Furthermore, a close relationship was observed between serum Mg-io and Mgi (r = 0.728, p < 0.001). We suggest that magnesium deficiency, both extracellular and intracellular, is a characteristic of chronic stable mild Type 2 diabetes, and as such, may predispose to the excess cardiovascular morbidity of the diabetic state. Furthermore, by more adequately reflecting cellular magnesium metabolism than total serum magnesium levels, Mg-io measurements may provide a more readily available tool than has heretofore been available to analyse magnesium metabolism in a variety of diseases.
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