Adrenergic Agonists

Question 1

1) pre-ganglionic release:
2) postganglionic parasympathetic release:
3) postganglionic sympathetic release:
4) adrenal medulla releases:
5) EXCEPTION: sympathetic fibers innervating sweat glands and some vascular smooth muscle release:

Answer 1

1) ACh –> N receptors
2) ACh –> M receptors
3) NE –> alpha and beta R
4) NE and EPI
5) ACh –> M receptors

Question 2

Parasympathetic System:

1) Eye
2) Heart
3) Bronchioles
4) GI tract
5) Bladder

Answer 2

1) pupillary constriction (miosis - contracts sphincter muscle); ciliary muscle (accomodation)
2) Negative chronotrophy (bradycardia)
3) constriction
4) increases motility
5) stimulates emptying

Question 3

Sympathetic System:

1) Eye
2) Bronchioles
3) Blood vessels
4) GI
5) Bladder
6) Metabolic functions
7) Heart

Answer 3

1) pupillary dilation (mydriasis - contracts dilator muscle); ciliary epithelium (produces aqueous humor)
2) smooth muscle relaxation
3) constriction and relaxation
4) decreases motility
5) inhibits emptying (contracts sphincter)
6) increases blood sugar
7) increase chronotropy and inotropy

Question 4

Alpha 1 Receptor
1)
2)
3)

Answer 4

Tissue - Action

1) vascular smooth muscle - contraction
2) pupillary dilator muscle - contracts (mydriasis)
3) pilomotor smooth muscle - contracts (erects hair)

Question 5

Alpha 2 Receptor
1)
2)

Answer 5

1) nerve terminals - inhibits neurotransmitter release

2) some vascular smooth muscle - vasoconstriction

Question 6

Beta 1 Receptor
1)
2)

Answer 6

1) Heart - stimulates rate and force

2) Juxtaglomerular cells - stimulates renin release

Question 7

Beta 2 Receptor
1)
2)

Answer 7

1) respiratory, uterine, and vascular smooth muscle - vasodilation
2) somatic motor nerve termials - causes tremor

Question 8

Dopamine 1 Receptor

1)

Answer 8

1) Renal and other splanchnic blood vessels - relaxes

Question 9

A1 signaling in vascular smooth muscle

Answer 9

(+) coupled to PLC ➝ IP3 ➝ intracellular Ca2+ ➝ Calcium-dependent protein kinase ➝ smooth muscle contraction

Question 10

A2 signaling in adrenergic nerve terminal

Answer 10

(-) coupled to Adenylyl Cyclase ➝ ↓cAMP ➝ ↓ PKA action ➝ ↓ phosphorylation of Ca-channels on nerve terminals ➝ ↓ Ca influx during depolarization ➝ ↓ neurotransmitter release

Question 11

A2 signaling in vascular smooth muscle

Answer 11

(-) coupled to Adenlyl Cyclase ↓cAMP ➝ inhibition of PKA ➝ activation of MLCK ➝ vascular smooth muscle contraction

Question 12

B1 signaling in pacemaker cells

Answer 12

(+) coupled to AC ➝ ↑ cAMP ➝ ↑ PKA phosphorylation of Ca channels ➝ ↑ inward Ca current during depolarization ➝ (+) chronotrophy

Question 13

B1 signaling in myocytes

Answer 13

↑ cAMP ➝ ↑ PKA phosphorylation of L-type Ca channels ➝ ↑ trigger Ca and SR storage ➝ (+) inotrophy

Question 14

B2 signaling in smooth muscle of brionchioles, uterus, and vascular smooth muscle

Answer 14

(+) coupled to AC ➝ ↑ cAMP ➝ ↑ PKA ➝ inactivation of MLCK ➝ reduced smooth muscle contraction

Question 15

Epinephrine

1) Physiological Effects
2) Indications
3) Toxicity
4) Contraindications
5) Half life

Answer 15

** at low doses, beta activation predominates; at high doses, alpha activation predominates **
1) low doses: ↓ Diastolic BP (B2), ↑ CO (B1)
high doses: ↑ TPR (A1 + A2 + B2) and CO (B2)
↑ bronchodilation (B2)
↓ bronchiole secretions (A1)
2) Anaphylaxis, cardiac arrest, bronchospasm
3) Arrhythmias**
4) later term pregnancy
5) SHORT

Question 16

Norepinephrine

1) Physiological Effects
2) Indications
3) Toxicity
4) Contraindications
5) Half-life

Answer 16

** LOW affinity for B2
1) ↑ CO (B1)
↑ TPR (A1 + A2)
↓ HR (Baroreceptor reflex to A1 + A2 + B2)
Overall ↑ MAP
2) limited to vasodilatory shock
3) Ischemia, arrhythmias
4) pre-existing vasoconstriction or ischemia
5) SHORT

Question 17

Dopamine

1) Physiological Effects
2) Indications
3) Toxicity
4) Contraindications
5) Half Life

Answer 17

** stimulates D1 receptors at low doses, stimulates A1/A2/B1 at high concentrations
1) low dose: ↓ TPR (D1)
medium dose: ↑ CO (B1)
high dose: ↑ TPR and MAP (A1 + A2 + B2)
2) cardiogenic shock
3) low BP (at low dose)**
ischemia (at high dose)**
4) tachyarrhythmia, VFib
5) 2 min

Question 18

Isoproterenol

1) Physiological Effects
2) Indications
3) Toxicity
4) Contraindications
5) Half Life

Answer 18

** non-selective B-agonist
1) ↓ TPR (B2)
↑ CO (B1)
(small) ↓ MAP
↑ HR (B1 + reflex to B2 ↓ MAP)
bronchodilation (B2)
2) Bradycardia / Heart block when TPR is high
3) Tachyarrhythmias**
4) angina with arrhythmias**
5) SHORT (catecholamine structure)