Exam 2: Beta Blockers Flashcards
1
Q
CNS neurotransmitters (list 6)
A
- Epinephrine
- Norepinephrine
- Dopamine
- Serotonin
- Gamma aminobutyric acid (GABA)
- Acetylcholine
2
Q
Agonists: natural vs. synthetic catecholamines
A
- Natural catecholamines:
- Epinephrine
- Norepinephrine
- Dopamine
- Synthetic catecholamines:
- Isoproterenol
- Dobutamine
3
Q
Alpha vs. Beta Adrenergic receptors
A
- ALPHA RECEPTORS (a) Receptors that respond with the following order of potency: Norepi > epi > isoproterenol
- Are termed alpha receptors.
- BETA RECEPTORS (b) Receptors that respond with the following order of potency:
- Isoproterenol > epi > norepi
- Are termed Beta receptors
4
Q
a1, a2, B1, B2 receptors
A
- a-1: Postsynaptic
- Found in: vasculature, heart, glands, and gut.
- Activation causes vasoconstriction and relaxation of the GI tract.
- a-2:
- Presynaptic
- Found in: Peripheral vascular smooth muscle, coronaries, brain.
- Activation causes inhibition of norepi release and inhibition of sympathetic outflow leading to ↓BP and ↓HR, inhibition of CNS activity.
- Ex: dexmedetomidine – sedation, inhibits release of NE → ↓ HR, relaxation/vasodilation – hypotension
- Negative feedback loop
- Postsynaptic
- Found in: Coronaries, CNS
- Activation causes constriction and sedation and analgesia
- All of the 1’s are post-synaptic (1, in 1 place), but all the 2’s are pre AND post-synaptic (2, 2 places)
- Presynaptic
- b-1:
- Found in: Myocardium, SA node, ventricular conduction system, coronaries, kidney.
- Activation causes: Increase in inotropy, chronotropy, myocardial conduction velocity, coronary relaxation, and renin release.
- b-2:
- Found in: Vascular, bronchial, and uterine smooth muscle, smooth muscle in the skin, myocardium, coronaries, kidneys, gi tract.
- Activation causes: vasodilation, brochodilation, uterine relaxation, gluconeogenesis, insulin release, potassium uptake by the cells.
5
Q
synthetic noncatecholes
A
- Ephedrine = Direct and Indirect (but mostly considered an indirect agent), alpha and beta
- Vasoconstriction and ↑ HR/inotropy
- 0.1-0.2 mg/kg
- 5-25 mg (increments of 5-10 mg)
- Elderly - Slower circulation time
- DOA – 15-1hr
- Can deplete catecholamine stores – decreasing effect “tachyphylaxis”
- Phenylephrine = Direct
- Pure alpha
- All vasoconstriction, reflex bradycardia (baroreceptor-mediated response)
- DOA – 5-20 minutes
- If youre giving repeated doses, will have to start a gtt
- 50- 100 mcg IV bolus
- 20-100 mcg/min gtt
- Nasal intubation
- Direct = works directly at the receptor
- Indirect = works to ↑ or ↓ the nt
- Trauma pt – 1) replete volume, 2) pick phenyl bc your HR is already up, don’t want to deplete catecholamines
6
Q
BP Equation
Where will alpha blockers work vs where beta blockers?
A
BP = CO x SVR
- Alpha blockers will work on the SVR side*
- Beta blockers will work on the CO side*
7
Q
a1 ARs: list the tissues they’re found in, and what action happens when they’re stimulated there
A
alphas are too tight (constriction)
- VSMCs - blood vessels, sphincters, bronchi
- contraction
- Iris (radial muscle) - contraction which DILATES the pupil
- Mydriasis: My-Dri-iris-DILATEs bc of the SNS response
-
piloerector smooth muscle
- erects hair
- prostate and uterus
- contraction
- Heart
- increase force of contraction
- but B1 is more important!!
8
Q
a2 ARs: list the tissues they’re found in, and what action happens when they’re stimulated there
A
- platelets
- aggretation
- adrenergic & cholinergic nerve terminals (presynaptic)
- inhibits transmitter release
- ↓ BP, ↓ HR
- VSMC
- post-synaptic = contraction
- pre-synaptic or CNS = dilation
- GI tract
- relaxation (presynaptic)
- CNS
- sedation and analgesia via ↓ SNS outflow from brainstem
9
Q
B1 ARs: list the tissues they’re found in, and what action happens when they’re stimulated there
A
- heart
- ↑ chronotropy, ↑ inotropy
- kidneys
- stimulation of renin release
10
Q
B2 ARs: list the tissues they’re found in, and what action happens when they’re stimulated there
A
- respiratory, uterine, vascular, GI, GU (visceral smooth muscle)
- smooth muscle relaxation
- mast cells
- decreases histamine release
11
Q
B3 ARs: list the tissues they’re found in, and what action happens when they’re stimulated there
A
- fat cells
- activates lipolysis, thermogenesis
12
Q
D1 ARs: list the tissues they’re found in, and what action happens when they’re stimulated there
A
- smooth muscle
- post-synaptic location: dilates renal, mesenteric, coronary, cerebral blood vessels
13
Q
D2 ARs: list the tissues they’re found in, and what action happens when they’re stimulated there
A
- nerve endings
- presynaptic: modulates nt release, N/V
14
Q
describe alpha ARs
A
- GPCR
- Ligands: NE, Epi & DA (large doses)
- 3 subtypes of a1 & a 2
- a 1 smooth m, eye
- a 2 mainly presynaptic location
- A1 – excitatory
- ↑ Ca++ → calmodulin activation → ↑ actin-myosin interaction → sm muscle contraction
- A2 – inhibitory
- ↓ cAMP → ↓ NE release
15
Q
describe Beta ARs
A
- β1 β2 β3
- GPCR, Gs
- Activation of adenyl cyclase → ↑ cAMP → ↑kinase activation & phosphorylation
- Autonomic effector tissues - heart, kidney, liver, smooth m, skeletal muscle; fat cells
16
Q
classes of drugs to tx HTN (3)
A
- Sympathetic nervous system
- b-antagonists
- a1-antagonists
- Mixed a/b antagonists
- Centrally acting a2-agonists
- Renin-angiotensin-aldosterone system
- Angiotensin Converting Enzyme Inhibitors (ACEI)
- Angiotensin II Receptor Blockers (ARB)
- Diuretics
- Endothelium derived mediator and/or ion channel modulators
- Direct vasodilators (nitroprusside, hydralazine)
- Calcium channel antagonists - not a 1st-line choice for HTN
- Potassium channel opener
17
Q
Tx guidelines for HTN
A
- Joint National Committee on Prevention, Detection, and Treatment of High Blood Pressure (JNC 8)
- Normal BP 120/80 should initiate “Lifestyle Modifications”
- Treatment thresholds/goals
- Age 18-59y.o. with no comorbidities and 60 and older with diabetes and/or chronic kidney disease <140/90
- Age 60 or older <150/90 with NO diabetes or kidney dz
- First-line therapy is thiazide diuretic unless there is a “compelling indication”
- Co-morbidity such as renal dz, DM, etc.
- Most patients will require at least 2 medications to reach goal
