Aldosterone
Actions
- stimulates sodium re-absorption from lumen of distal nephron in exchange
for potassium or hydrogen
- induces formation of proteins involved in sodium
transport
Release
- stimulated by angiotensin II
- renin release by decrease in perfusion pressure in
afferent arterioles of kidney
- cleaves angiotensinogen to angiotensin I
- angiotensin I converted to angiotensin II by converting
enzyme in endothelial cells
- plasma potassium concentration and ACTH also stimulate
aldosterone release
Drugs
- spironolactone
- blocks actions of aldosterone
Problems
- Hyperaldosteronism (Conn's syndrome if
caused by adrenal adenoma)
- in excess blood volume increased so hypertension,
- continued high potassium excretion leads to Hypokalaemia
Metabolism
- in liver then conjugated with a glucuronide for excretion
in urine
- increased sodium transport leads to increased potassium
excretion
- in excess blood volume increased so hypertension, continued
high potassium excretion leads to hyperkalemia
14.4.2.2 Aldosterone
| mineralocorticoid action to regulate body
sodium and water |
|
| control of mineralocorticoid secretion via
renin-angiotensin, ANP, ions |
|
| dysfunction: aldosterone excess (Conn’s) |
|
|