Question #306
Aldosterone
Aldosterone is a mineralocorticoid hormone secreted by the zona glomerulosa of the adrenal cortex. Angiotensin-II is the main secretagogue. As a steroid hormone, aldosterone crosses the cell membrane to act on intracellular receptors. In the collecting ducts it causes the loss of K+ and retention of Na+.
Excess, as in Conn’s syndrome, is associated with hypernatraemia, hypervolaemia and hypertension, as well as hypokalaemia and alkalosis.
Deficiency, as in Addison’s disease, is associated with circulatory collapse, as well as hyperkalaemia and alkalosis.
See A Thinking Approach to Physiology
, pages 172 - 174.