Essentials of Clinical Nephrology (Shorouk Press, Cairo, 2000, ISBN ...

C- Hormones acting on the kidney:
1- Antidiuretic hormone (vasopressin): ADH is produced by the cells of
the supraoptic nucleus of the hypothalamus and is released from the
posterior pituitary.
The major effects of ADH are: (1) it increases collecting tubule
permeability to water allowing it to flow back to circulation. This leads to
urine concentration and water retention; and (2) it causes
vasoconstriction, leading to a rise in the arterial blood pressure.
Stimuli to secretion of ADH include: (1) decrease in effective blood
volume, this triggers pressure sensors in cardiac atria, aortic arch and
carotid sinuses. The response curve is exponential. Therefore, the
volume stimuli override osmolar stimuli. By this mechanism decreased
effective blood volume as in cirrhosis and cardiac failure results in
excess secretion of ADH with water retention irrespective of the
developing hyponatremia (dilution) and hypo-osmolarity; (2) increase in
plasma osmolarity, sensitive osmoreceptors exist in the hypothalamus,
and the response is linear. Sodium chloride is a powerful stimulant for
secretion of ADH, while urea, glucose and ethanol are very weak
stimulants; and (3) Many other stimuli, including nausea,
hypoglycemia, high ambient temperature, anxiety and stress are also
associated with release of ADH.
Synthetic analogues of ADH include the following : (1) 8-arginine
vasopressin-AVP, which is available for parentral or intranasal use in
ADH deficiency; and (2) Desamino-D-arginine vasopressin (DDAVP) is
a synthetic analogue which has increased antidiuretic but decreased
vasoconstrictor effect compared with AVP.
2- Atrial natriuretic peptide (ANP), ANP is a 28 amino acid peptide
which is released from granules in the cardiac atria in response to
stretch. ANP has renal (diuretic and natriuretic) and hemodynamic
(hypotensive) effects. It also has important hormonal actions such as
suppression of renin and aldosterone.
3- Mineralocorticoids and glucocorticoids: Aldosterone is a steroid
hormone produced by the adrenal cortex in response to
adrenocorticotrophic hormone, hyperkalaemia or angiotensin II. Its