ADH
🏠 synthesis: neurons from supraoptic nuclei → project through infundibulum of hypothalamus to Posterior pituitary
Net effect: concentrates urine, ↑ water reabsorption
- Binding site: V2 receptors 🏠 DCT and collecting ducts
- ⇒ ↑ incorporation of AQP-2 channels in apical membrane
- ↑ water resorption and retention - so ↑ urine osmolality
- Binding to V1 receptors ⇒ vasoconstrictors
- acts on vascular, splanchnic, renal, coronary circulation
- less arrhythmogenic than adrenaline
Homeostasis
Stimulus/trigger
- ↑ plasma osmolality
- sensor: osmoreceptor (hypothalamus)
- ↓ plasma volume
- sensor: baroreceptor (L atrium, aortic arch, carotid)
- signal: posterior pit via vagus nerve
- Angiotensin II
- sympathetic ns activity
Inhibition (i.e. stuff that makes you pee)
- Alcohol
- Caffeine
- ANP (when atria are stretched)
- Steroids, ADH receptor antagonists (e.g. tolvaptan)
- hypokalaemia?
pathology
can be used pharmacologically e.g. to manage ICP
remember this is the same as vasopressin!
Vasopressin as a vasopressor