(5) GI & Endo: Hypothalamic... (4.1-4.2) Flashcards
Where in the kidney are V2 receptors found?
Basolateral membrane of collecting duct
What type of G-protein is the V1 receptor?
Gq
Where are V1 receptors found?
Vascular smooth muscle
What type of G-protein is the V2 receptor?
Gs
Where outside the kidney are V2 receptors found?
Vascular endothelium
(Similar to endothelial M3 receptors which vasodilate by inducing NO release)
Other than increasing water permeability, what physiologic function does stimulation of V2 receptor mediate?
(1) ↑ vWF
(2) ↑ Factor VIII
* (Remember vWF stabilizes Factor VIII, preventing its degradation, so it’s logical they would be affected together)*
What is the most notable cause of drug-induced nephrogenic diabetes insipidus?
Lithium
What drugs can be used to treat nephrogenic diabetes insipidus?
(1) Thiazide diuretics
(2) Amiloride
(3) NSAIDs
Treatment: Lithium-induced diabetes insipidus
Amiloride
(Remember, thiazides and NSAIDs will REDUCE clearance of lithium)
Treatment: Central diabetes insipidus
(1) Exogenous ADH
(2) Desmopressin
* (So ∴ ADH or an ADH analog)*
What is the receptor specificity of Desmopressin?
V2 Selective
(Desmospressin = DDAVP, 2 ds = V2)
Treatment - Pharmacologic: Hemophilia A
Desmopressin
Indications (4) : Desmopressin
(1) Central diabetes insipidus
(2) vWF deficiency
(3) Hemophilia A
(4) Enuresis
Name the potential electrolyte abnormality caused by Desmopressin
Hyponatremia
(↑ Absorption of free water ⇒ Dilution of electrolytes)
How does ADH help to treat esophageal variceal bleeding?
Mesenteric vasoconstriction
(↓ Portal pressure)
Suffix: V2 receptor antagonists
“-vaptan”
What is the most severe potential adverse effect of V2 receptor agonists?
Central pontine myelinolysis
(Osmotic demyelination syndrome - ue to rapid correction of hypernatremia)
What antibiotic can be used to treat SIADH?
Demeclocycline
What class of receptor is the growth hormone receptor?
Non-receptor tyrosine kinase
(JAK and his beanstalk)
What protein is predominantly responsible for growth?
IGF-1
Where is IGF-1 produced?
Liver
(Predominantly)
Differentiate growth hormone’s effect on skeletal muscle and adipose tissue
(1) Skeletal muscle: Anabolic
(2) Adipose tissue: Catabolic
Indications (3) : Growth hormone (short stature)
(1) Idiopathic
(2) Prader-Willi syndrome
(3) Turner syndrome
MOA: Mecasermin
IGF-1 analog
What is the difference in how growth hormone and IGF-1 affect serum glucose?
(1) Growth hormone: ↓ Insulin sensitivity
(2) IGF-1: Insulin-like properties
What do you call it when an adult has a GH secreting tumor? A child?
(1) Adult: Acromegaly
(2) Child: Gigantism
What drug can be used to inhibit growth hormone secretion?
Octreotide
(Somatostatin analog, given if GH levels remain high after surgical resection)
Octreotide can be used to inhibit tumors secreting what 6 hormones?
(1) Growth hormone
(2) VIP
(3) Serotonin
(4) Insulin
(5) Glucagon
(6) Gastrin
Treatment (2) : Esophageal variceal bleeding
(1) ADH
(2) Octreotide
Adverse Effects (2) : Octreotide
(1) GI upset
(2) Steatorrhea
* (Inhibits digestive enzymes. e.g., ⇒ ↓ CCK ⇒ ↓ Bile acid ⇒ Gallstones)*
Name 2 D2 receptor agonists used to treat acromegaly
(1) Cabergoline
(2) Bromocriptine
* (Bromocriptine ∝ Burgler)*
MOA: Pegvisomant
GH receptor antagonist
(May actually ↑ GH levels due to reduced negative feedback)
MOA: Cabergoline
D2 receptor agonist
