Joëlle Schutten

Chapter 4 82 that magnesium infusion decreased aldosterone production 21. Later, they observed that magnesium counteracts angiotensin II, suggesting that magnesium indirectly inhibits the production of aldosterone 22. Additionally, a direct effect of magnesium on aldosterone production was reported in a study by another group 23. In this study, angiotensin II levels were unchanged in magnesium deficient rats compared to healthy animals, and magnesium supplementation did not affect angiotensin II levels in these rats. In contrast, aldosterone levels did change after magnesium supplementation, suggesting that magnesium affects aldosterone production independent of angiotensin II. In untreated hypertensive subjects, renin levels were negatively correlated with serum magnesium levels and positively correlated with serum calcium levels 26. How magnesium might affect the actions of angiotensin II and production of aldosterone at the molecular level remains unknown. It has been suggested that the actions of angiotensin II are mediated by an increase in intracellular calcium 27, and magnesium might decrease these intracellular calcium concentrations 28. Also, magnesium might activate membrane-Na+K+-ATPase in cardiac muscle cells, resulting in decreased intracellular sodium and calcium 29. Thus, magnesium may decrease sodium and fluid reabsorption through direct and/or indirect inhibition of aldosterone production. Atrial natriuretic peptide Dietary magnesium intake has also been shown to influence atrial natriuretic peptide release in rats.30 After inducing hypermagnesaemia, circulating atrial natriuretic peptide levels were increased due to increased release from the heart. Magnesium and total peripheral resistance Total peripheral vascular resistance is a major component of BP: as the peripheral resistance increases, BP is also increased. Peripheral resistance, in turn, depends on vascular structure (including the presence of calcifications) and function, with the endothelium being an important regulator. In addition, the sympathetic nervous system and several hormones regulate vascular tone, providing a major contribution to vascular resistance.

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