(5) GI & Endo: Hypothalamic... (4.1-4.2)

Question 1

Where in the kidney are V2 receptors found?

Answer 1

Basolateral membrane of collecting duct

Question 2

What type of G-protein is the V1 receptor?

Answer 2

Gq

Question 3

Where are V1 receptors found?

Answer 3

Vascular smooth muscle

Question 4

What type of G-protein is the V2 receptor?

Answer 4

G_s

Question 5

Where outside the kidney are V2 receptors found?

Answer 5

Vascular endothelium

(Similar to endothelial M3 receptors which vasodilate by inducing NO release)

Question 6

Other than increasing water permeability, what physiologic function does stimulation of V2 receptor mediate?

Answer 6

(1) ↑ vWF
(2) ↑ Factor VIII
* (Remember vWF stabilizes Factor VIII, preventing its degradation, so it’s logical they would be affected together)*

Question 7

What is the most notable cause of drug-induced nephrogenic diabetes insipidus?

Answer 7

Lithium

Question 8

What drugs can be used to treat nephrogenic diabetes insipidus?

Answer 8

(1) Thiazide diuretics
(2) Amiloride
(3) NSAIDs

Question 9

Treatment: Lithium-induced diabetes insipidus

Answer 9

Amiloride

(Remember, thiazides and NSAIDs will REDUCE clearance of lithium)

Question 10

Treatment: Central diabetes insipidus

Answer 10

(1) Exogenous ADH
(2) Desmopressin
* (So ∴ ADH or an ADH analog)*

Question 11

What is the receptor specificity of Desmopressin?

Answer 11

V2 Selective

(Desmospressin = DDAVP, 2 ds = V2)

Question 12

Treatment - Pharmacologic: Hemophilia A

Answer 12

Desmopressin

Question 13

Indications (4) : Desmopressin

Answer 13

(1) Central diabetes insipidus
(2) vWF deficiency
(3) Hemophilia A
(4) Enuresis

Question 14

Name the potential electrolyte abnormality caused by Desmopressin

Answer 14

Hyponatremia

(↑ Absorption of free water ⇒ Dilution of electrolytes)

Question 15

How does ADH help to treat esophageal variceal bleeding?

Answer 15

Mesenteric vasoconstriction

(↓ Portal pressure)

Question 16

Suffix: V2 receptor antagonists

Answer 16

“-vaptan”

Question 17

What is the most severe potential adverse effect of V2 receptor agonists?

Answer 17

Central pontine myelinolysis

(Osmotic demyelination syndrome - ue to rapid correction of hypernatremia)

Question 18

What antibiotic can be used to treat SIADH?

Answer 18

Demeclocycline

Question 19

What class of receptor is the growth hormone receptor?

Answer 19

Non-receptor tyrosine kinase

(JAK and his beanstalk)

Question 20

What protein is predominantly responsible for growth?

Answer 20

IGF-1

Question 21

Where is IGF-1 produced?

Answer 21

Liver

(Predominantly)

Question 22

Differentiate growth hormone’s effect on skeletal muscle and adipose tissue

Answer 22

(1) Skeletal muscle: Anabolic
(2) Adipose tissue: Catabolic

Question 23

Indications (3) : Growth hormone (short stature)

Answer 23

(1) Idiopathic
(2) Prader-Willi syndrome
(3) Turner syndrome

Question 24

MOA: Mecasermin

Answer 24

IGF-1 analog

Question 25

What is the difference in how growth hormone and IGF-1 affect serum glucose?

Answer 25

(1) Growth hormone: ↓ Insulin sensitivity
(2) IGF-1: Insulin-like properties

Question 26

What do you call it when an adult has a GH secreting tumor? A child?

Answer 26

(1) Adult: Acromegaly
(2) Child: Gigantism

Question 27

What drug can be used to inhibit growth hormone secretion?

Answer 27

Octreotide

(Somatostatin analog, given if GH levels remain high after surgical resection)

Question 28

Octreotide can be used to inhibit tumors secreting what 6 hormones?

Answer 28

(1) Growth hormone
(2) VIP
(3) Serotonin
(4) Insulin
(5) Glucagon
(6) Gastrin

Question 29

Treatment (2) : Esophageal variceal bleeding

Answer 29

(1) ADH
(2) Octreotide

Question 30

Adverse Effects (2) : Octreotide

Answer 30

(1) GI upset
(2) Steatorrhea
* (Inhibits digestive enzymes. e.g., ⇒ ↓ CCK ⇒ ↓ Bile acid ⇒ Gallstones)*

Question 31

Name 2 D2 receptor agonists used to treat acromegaly

Answer 31

(1) Cabergoline
(2) Bromocriptine
* (Bromocriptine ∝ Burgler)*

Question 32

MOA: Pegvisomant

Answer 32

GH receptor antagonist

(May actually ↑ GH levels due to reduced negative feedback)

Question 33

MOA: Cabergoline

Answer 33

D₂ receptor agonist