Aldosterone

Physiology

It is synthesized on the level of the zone glomérulée of the gland suprarenal and secreted directly in blood circulation.

Its synthesis is activated by angiotensin II (Système renin-angiotensin-aldosterone), by the Potassium, ACTH, and the endothèline 1.

It acts thanks to a specific receiver, called mineralocorticoid Récepteur (MR.), whose essential function is the regulation of the hydro-containing soda balance (reabsorption active of Sodium and passive of water) and consequently of the blood pressure which is dependant for him. This receiver is expressed on the distal circumvented level tubule of the kidney and babbit metal directly the form of genes coding for the proteins which control the reabsorption of Sodium (Na⁺) and the excretion of Potassium (K⁺). These proteins are mainly the epithelial Canal with sodium (ENaC), and the pump Na⁺/K⁺.

One also finds receivers on the level:

of the epithelial cells of the colonist (absorption of sodium)
of the central nervous system (hippocampus, regulation of the containing soda appetite)
of the smooth muscular cells of the vessels (regulation of the blood pressure)
of the cardiac cells

It would support by its last the production of Collagène what would involve an increase in vascular resistances and an increase in the Blood-pressure.

Proportioning

It can be proportioned in the Sang ( aldosteronemy ) and in the Urine S ( aldostéronurie ).

Pathology

A too high secretion of aldosterone is called a Hyperaldostéronisme , a too low secretion a hypoaldosteronism . It is primarily the first most frequent case. It appears by a arterial Hypertension.

It is known as secondary if the increase in this hormone is consequence of a stimulation of its production by a physiological mechanism. Otherwise, it is called primary .

In addition the physiological secretion of aldosterone can be noxious in certain diseases: it is the case of the Cardiac failure where the blocking of its production or its action constitutes one of the keys of the treatment.

Role in pharmacology

The activity of this hormone can be braked:

by reduction in its production by the inhibiting of the enzyme of conversion preventing the conversion of angiotensin I into angiotensin II. Antagonistic of the receivers of angiotensin II (" sartans") acts in the same way. Other drugs inhibit this way indirectly. It is the case in particular Bêta-bloquant S.
by blocking of the receivers. They are the anti-aldosterones whose leader is the Spironolactone.

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