Aldosterone Dr Grrishma B Adrenal gland Essential for

Aldosterone Dr. Grrishma B

Adrenal gland • Essential for survival • Mainly adrenal cortex hormones are important for survival.

Adrenal Cortex – comprises 90% of the gland The cortex – further subdivided into three zones: 1. the outer zone, the zona glomerulosa 2. middle zone, the zona fasciculata 3. inner zone, the zona reticularis. –

• These zones produce steroid hormones.

Aldosterone • • • Major mineraocorticoid Secreted from zona glomerulosa Aldosterone Desoxycorticosterone 9α fluorocortisol (synthetic) • Normal concentration of aldosterone is 6 nanograms/100 ml, average secretion is about 150 micrograms/day

Regulation • Angiotensin II stimulates aldosterone synthesis. • ACTH stimulates aldosterone synthesis transiently. • Hyperkalemia stimulates aldosterone synthesis

Mechanism of action • Genomic – sgk gene increases ENAC synthesis and activity

Physiological actions • Electrolyte and water balance • Na absorption and promote K+ and H+ secretion in the kidney (acts on P cells of collecting duct and DCT) • Increases number of Na channels in cell • Increases Na-K ATPase activity • Stimulates enzymes of kreb cycle for generation of ATP

• As Na is resorbed Cl- is also transported along with H 2 O.

On sweat glands and salivary glands. sodium is reabsorbed from sweat glands and salivary glands It helps to conserve salts

Why essential for life? Without them ECF K+ Na+ and Cl. ECF volume cardiac dysfunction, shock and death. • Therefore it is called the life saving portion of corticosteroids

Aldosterone escape • Stimulates secretion of ANP from the atrial muscles of the heart. • ANP causes excretion of sodium in spite of aldosterone secretion • It causes excretion of excess salt and water through urine (pressure diuresis) • The content of ECF becomes normal inspite of hypersecretion of aldosterone • Normality of salt and water content of the body

aldosterone Na+ ions are retained in the body osmotic absorption of water ECF volume arterial pressure ANP pressure diuresis – excretion of salt and water. • This secondary increase in water and salt excretion by the kidneys is called aldosterone escape.

Deficiency of aldosterone • • Loss of sodium and chloride ions Excess of potassium ions Fluid and blood volume decreases Diminished cardiac output Shock like state Death in 3 days to 2 weeks Mineralocorticoid is life saving hormone of adrenal gland

Dysfunctions- increase • Primary Hyper aldosteronism (Conn’s syndrome) • Secondary Hyper aldosteronism

Primary Hyper-aldosteronism (Conn’s syndrome) • This is termed hyper aldosteronism. • This occurs due to adenoma of zona glomerulosa. • In this condition, there is K+ depletion, Na+ retention, weakness, hypertension, tetany, polyuria and alkalosis. • Reduced renin secretion • No edema because of aldosterone escape phenomenon • Treatment – removal of tumor

Primary secondary

Primary secondary

Secondary Hyper aldosteronism • This occurs due nephrosis, cirrhosis of liver and congestive cardiac failure. • Increased renin release • Renal artery constriction produces increased renin and aldosterone secretion