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Renal 03 Vasopressin
Maloney Pharmacology of Vasopressin
Question | Answer |
---|---|
Vasopressin is the main hormone involved in what? | The regulation of body fluid osmolality |
What can stimulate vasopressin (ADH) release? | High plasma osmolality, major hypovolemia, and major hypotension |
Where are the vasopressin receptors located? | V1 on vascular smooth muscle : V2 on principal cells of renal collecting duct and vascular epithelium |
What are the results of binding to V1? | Causes vasoconstriction in vascular smooth muscle |
What happens when vasopressin binds to V2? | V2 receptors on vascular endothelium will release clotting favtor VIII and vWF from storage sites |
Without vasopressin, what kind of urine is produced? | Dilute urine |
The V2 receptor on the basolateral membrane in the collecting duct coupes to Gs. What signaling pathway is activated/inhibited? | This activates adenylyl cyclase. |
With vasopressin, what type of urine is produced? | Concentrated urine |
What cells in the collecting ducts do vasopressin bind to? | It binds to the basolateral membrane of principal cells |
What does activating Gs do? | Activates adenylyl cyclase and increases cAMP |
Increased cAMP will activate what? | Protein kinase A, which will induce water channels to move to the apical membrane, increasing water permeability |
Name the two vasopressin agents. | Vasopressin and desmopressin |
What is the half-life, receptor(s), and route(s) of administration for vasopressin? | Short acting (half-life about 10 minutes) : Binds both V1 and V2 : IM, SC, IV |
What is the half-life, receptor(s), and route(s) of administration for desmopressin? | Long acting (half-life about 75 minutes) : Binds V2>>>V1 : IV, SC, intranasal, oral |
Which agent will selectively affect urine output? | Desmopressin |
Name the clinical uses for vasopressin. | Advance Cardiac Life Support : Vasodilatory shock |
What is a clinical use for desmopressin? | Primary nocturnal enuresis (bed wetting) - use for 4-8 weeks in children >6 with severe NE |
How does this happen? | Binds to V2 in the kidney -> increases water permeability in the collecting duct -> increase water reabsorption -> decrease urine output |
Other clinical uses of desmopressin. | Hemophillia A or type I von Willebrand's disease - increase circulating levels of factor VIII and vWF and shorten bleeding time : Central diabetes insipidus |
Where is the issue in Central diabetes insipidus? | The posterior pituitary does not release vasopressin |
Why does desmopressin not work in nephrogenic D.I.? | The V2 receptors have insufficient response to binding. |
A two year old boy is diagnosed with nephrogenic diabetes insipidus. What drug will be most useful in treating him? | Hydroclorothiazide |
Why do you give desmopressin for central DI and not vasopressin? | Desmopressin is selective for V2 causing less side effects |
What are the adverse effects seen with vasopressin (V1) | Facial pallor, transient headache, nausea, abdominal cramps, hypertension, coronary vasospasm |
Adverse effects associated with vasopressin and desmopressin (V2) | Water intoxication, hyponatremia (hypervolemia hyponatremia) |
Why do you not use intranasal desmopressin to treat bed wetting? | It can cause DEATH |
Adverse effects with intranasal desmopressin. | Congestion and rhinitis |