39. ADH

[Editor]

a) acts at the collecting ducts by increasing levels of cyclic AMP
b) is produced form the supraoptic nuclei of the thalamus
c) is a polypeptide containing 10 amino acids
d) levels are decreased by alcohol
e) ectopic release occurs in pulmonary adenocarinomas

[Editor]

TFFTF

ADH or arginine vasopressin is synthesized in the supra-optic nuclei of the hypothalamus and stored in the posterior pituitary gland ready for release. It contains 9 amino acids and is a polypeptide. Its actions are via the cAMP second messenger system which causes an up regulation of water channels in the collecting ducts. Its release is under the control of baroreceptors and osmoreceptors via the hypothalamus.
Levels are reduced by alcohol consumption leading to dehydration with excess use. Ectopic ADH (SIADH) does occur with pulmonary tumors however these are of the small (oat) cell histopathology.