Patients with primary aldosteronism, which is the most prevalent form of secondary
hypertension, have an increased rate of cardiovascular events, compared to patients with
essential hypertension, even with equal severity of hypertension. This might be partially
attributed to the association of increased aldosterone levels with insulin resistance. How
this relation can be explained from a pathophysiological point of view, is insufficiently
established.
Recently, microvascular dysfunction has been proposed as a link between insulin resistance
and hypertension. Loss of NO-mediated vasodilation is an important feature of microvascular
dysfunction; in addition, an impaired insulin-mediated microvascular NO production has been
suggested to underlie the reduction in insulin-stimulated glucose disposal that is
characteristic of insulin-resistant states. Increased aldosterone levels are not only
associated with insulin resistance, but also with endothelial dysfunction. In addition, they
interfere with the vascular effects of insulin.
Therefore, the investigators hypothesize that in patients with primary aldosteronism,
increased aldosterone levels induce microvascular dysfunction through reduction of
NO-availability, which contributes to the development of insulin resistance, and of
hypertension, in addition to the sodium-retaining effects of aldosterone.