Aldosterone and cardiovascular risk.

Through its classic effects on sodium and potassium homeostasis, aldosterone, when produced in excess, is associated with the development of hypertension and hence with higher cardiovascular and renal risk. In recent years, experimental and epidemiologic data have suggested that aldosterone also may be linked to high cardiovascular risk independently of its effects on blood pressure. Thus, aldosterone has been associated with obesity and metabolic syndrome in selected populations, and these associations may further contribute to the higher cardiovascular risk of subjects with elevated aldosterone levels. Moreover, aldosterone has been reported to promote inflammation, oxidative stress, and fibrosis in a number of tissues. Clinical evidence indicates that patients with primary hyperaldosteronism have a higher risk of developing cardiovascular and renal complications than patients with essential hypertension who have the same level of blood pressure. Aldosterone receptor blockade has been shown to lower cardiovascular mortality after myocardial infarction and in patients with congestive heart failure. Some studies have also demonstrated that aldosterone blockade could have a favorable impact on the progression of renal disease. However, prospective interventional trials are needed to further evaluate the impact of blockade of aldosterone on cardiovascular risk

Aldosterone deficiency prevents high-fat-feeding-induced hyperglycaemia and adipocyte dysfunction in mice

AIMS/HYPOTHESIS: Obesity is associated with aldosterone excess, hypertension and the metabolic syndrome, but the relative contribution of aldosterone to obesity-related complications is debated. We previously demonstrated that aldosterone impairs insulin secretion, and that genetic aldosterone deficiency increases glucose-stimulated insulin secretion in vivo. We hypothesised that elimination of endogenous aldosterone would prevent obesity-induced insulin resistance and hyperglycaemia. METHODS: Wild-type and aldosterone synthase-deficient (As(−/−)) mice were fed a high-fat (HF) or normal chow diet for 12 weeks. We assessed insulin sensitivity and insulin secretion using clamp methodology and circulating plasma adipokines, and examined adipose tissue via histology. RESULTS: HF diet induced weight gain similarly in the two groups, but As(−/−) mice were protected from blood glucose elevation. HF diet impaired insulin sensitivity similarly in As(−/−) and wild-type mice, assessed by hyperinsulinaemic–euglycaemic clamps. Fasting and glucose-stimulated insulin were higher in HF-fed As(−/−) mice than in wild-type controls. Although there was no difference in insulin sensitivity during HF feeding in As(−/−) mice compared with wild-type controls, fat mass, adipocyte size and adiponectin increased, while adipose macrophage infiltration decreased. HF feeding significantly increased hepatic steatosis and triacylglycerol content in wild-type mice, which was attenuated in aldosterone-deficient mice. CONCLUSIONS/INTERPRETATION: These studies demonstrate that obesity induces insulin resistance independently of aldosterone and adipose tissue inflammation, and suggest a novel role for aldosterone in promoting obesity-induced beta cell dysfunction, hepatic steatosis and adipose tissue inflammation