Cardio: Adrenergic Drugs Flashcards Preview

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Flashcards in Cardio: Adrenergic Drugs Deck (29)
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1

  • Affects:
    • α1, α2
    • β1

Norepinephrine

2

  • Affects:
    • α1, α2

    • β1, β2, β3

Epinephrine

3

  • Affects:
    • β1, β2, β3
    • D1 (& D5), D2 (& D3, D4)
    • At high concentrations: α1

Dopamine

4

Adrenergic receptors of the
Heart

  • β1 = Increased contractility
  • β1 = Increased automaticity
  • β1 = Increased conduction velocity

5

Adrenergic receptors fo the
Blood Vessels

  • α1 = Arteriolar constriction
  • β2 = Arteriolar dilation of Skeletal muscle and Liver
  • D1 = Arteriolar dilation of Kidney and Mesentry
     
  • α1 = Venoconstriction
  • β2 = Venodilation

6

Adrenergic receptors of the 
Bronchioles

  • β2 = Bronchodilation

7

Adrenergic receptors of the 
Iris

  • α1 = Radial muscle contraction --> mydriasis

8

Adrenergic receptors of the 
GI Tract and Urinary Bladder

  • α1 = Sphincter contraction
  • β2 = Decreased motility

9

Adrenergic receptors of the 
Uterus

  • β1 = Relaxation of uterus

10

Metabolic affects of adrenergic receptors on the 
Liver

  • α1 / β2 = Gluconeogenesis, Glycogenolysis

11

Metabolic affects of adrenergic receptors on the
Fat

  • β1 / β3 = Lipolysis

12

Metabolic affects of adrenergic receptors on the
Pancreas

  • α2 = Decreased insulin secretion

13

Metabolic affects of adrenergic receptors on the
 Kidney

  • β1 = Renin secretion

14

  • These receptors include typical postsynaptic receptors mediating smooth-muscle contraction

α1

15

  • These receptors include presynaptic autoregulatory and postsynaptic receptors
    • Activation of prysynaptic autoregulatory inhibits NE release while blockage of the presynaptic receptors enhances NE releaase
    • Postsynaptic receptors exist in extrasynaptic vascular smooth muscle, ciliary, epithelium, and in the brain

α2

16

Mechanism of Transduction 
β1

  • Gs protein
  • Increases adenylyl cyclase activity
  • Opens L-type Ca2+ channels

17

Mechanism of Transduction 
β2

  • Gs protein
  • Increases adenylyl cyclase activity

18

Mechanism of Transduction 
β3

  • Gs protein
  • Increases adenylyl cyclase activity

19

Mechanism of Transduction 
α1

 

  • Gq protein
  • Increases phospholipase C --> Increases IP3
    --> Increases Ca2+
     
  • Increases phospholipase D (Minor effectors)
     
  • Gq, Gi/Go
  • Increases phospholipase A2 (Minor effectors)

20

Mechanism of Transduction 
α2

 

  • Gi protein
  • decreases adenylyl cyclase activity
     
  • Gi (via βy subunits)
  • Opens K+ channels (L- and N- types)
     
  • Go
  • Closes Ca2+ channels

21

Epinephrine cardiac effects

  • β1 actions
  • Increases automaticity, Heart Rate, Conduction velocity, Myocardial contractile force (MCF), Cardiac output (CO), and O2 consumption
  • Accelerates phase 4 diastolic depolarization in Purkinje fibers and further facilitates activation of latent pacemaker cells
  • Can cause ventricular arrhythmias (especially in the presence of halogenated hydrocarbon anesthetics)

22

Epinephrine vascular effects on 
peripheral resistance and blood pressure

  • Increases Cutaneous, Mesenteric, and Renal vascular resistance (α1 receptor)
  • Decreases Skeletal and Liver vascular resistance at low concentrations (β2 receptor > α1 receptor) --> dilation
  • Increases Skeletal and Liver vascular resistance at high concentrations (α1 receptor > β2 receptor) --> constriction
  • Low Dose Epi - decrease BP (β2) vasodilation, increase HR (β1)decrease or no change in Mean Blood Pressure (MBP)
  • High Dose Epi - Increase MBP (α1) both Sys / Dia

23

Epinephrine nonvascular effects on 
Bronchiole Smooth Muscle

  • Relaxes Bronchal smooth muscle (β2)
  • Most evident when bronchial muscle is contracted due to disease or drugs

24

Epinephrine Metabolic effects

  • Hyperglycemia occurs due to gluconeogenesis and glycogenolysis in the Liver (α1 / β2)
  • Inhibition of insulin release (α2) from Pancreas
  • Lipolysis elevates free Fatty Acids in the blood (β1 and β3)

25

Norepinephrine effects the
Blood pressure and Vasculature

  • Increases peripheral resistance in most vascular beds (α1) with no dilation anywhere
  • Increases Total peripheral resistance (TRP)
  • Increases Mean Blood Pressure (MBP)
     
  • Decreases Blood flow in the Skin, Kidney, Liver, and Skeletal muscle w/ flow to CNS not reduced

26

Norepinephrine cardiac effects

  • β1 actions same as Epinephrine
  • Heart rate decreases due to compensatory Vagal reflex activity initiated by the elevated MBP; overcomes the direct cardioacceleratory action of β1 receptor activation

27

α receptor general locations

  • α1 - post-synaptic
  • α2 - pre and post-synaptic (β cells of the Pancreas)

28

β receptor general locations

  • β1 - post-synaptic
  • β2 - extra-junctional on EO (end organs)
    • NEVER at synaptic nerve terminal
  • β3 - 

29

D receptor general locations

  • D1 - post-synaptic
  • D2 - pre and post-synaptic