Adrenergic Receptor Agonists

Question 1

a1

Answer 1

Postsynaptic
Gq coupled-> phosphodiesterase

Effects
   Vasoconstiction
   GIT SM relaxation
   Salivary secretion
   Contraction of ureter, pregnant uterus, bronchioles, 
       seminal tract, sphincters
   Glucogenolysis and gluconeogenesis
   Na resorption from kidney
   Neuronal effect: anorexia, decrease glutaminergic 
       excitatory postsyn potential

Question 2

a2

Answer 2

Presyn on adrenergic nerve terminals
Postsyn on SM of vessels and platelets
Pancreas
Gi coupled: inhibit adenylate cyclase

Inhibit transmitter release
Inhibit lipolysis
Inhibit insulin secretion
Vascular SM contraction: vaso and venoconstriction 
Platelet aggregation

Question 3

b1

Answer 3

Predominantly cardiac
Gs coupled: activate adenylate cyclase

AV, SA, Atrial and ventricular muscle, His- Purkinje (increased automaticity and conduction velocity)

Positive chrono- (HR in SA)
dromo- (conduction velocity AV Node)
inotropic (Increased atrial and ventr contractility)

Also found in kidney: increase renin release

Question 4

b2

b3

Answer 4

Gs coupled: activate adenylate cyclase

SM relaxation: uterus, GIT, M detrusor urinae, bronchi

Blood vessel: vasodilation

Liver: glycogenolysis

Pancreas: Increase insulin secretion

Skeletal muscle: -> contraction

b3: Gs Thermogenesis; lipolysis in adipose tissue

Question 5

Dopamine Rs

Answer 5

D1: Gs
vasodilation of afferent renal vessels
(also present in mesenteric and coronaries)

D2: Gi

Question 6

Affinities

Answer 6

NE: a1=a2
b1»>b2

Epinephrine: a1=a2
b1=b2

Question 7

CV Effects of Adrenergic R Agonists

Answer 7

Vasoconstriction via a1 or a2
Vasodilation via b2
—> Effects of above added; result depends on agonist
selectivity

Positive ino, dromo, chromotropic via b1
reflex brady if drug-> bronchoconst and vasoconst
in response to increase BP

Question 8

Respiratory Effects of Adrenergic R Agonists

Answer 8

Bronchodilation via b2

Question 9

GIT Effects of Adrenergic R Agonists

Answer 9

SM relaxation via a1, b2

Increased sphincter tone via a1

Question 10

Metabolic Effects of Adrenergic R Agonists

Answer 10

Glycogenolysis: Increased glucose via a1, b2

Lipolysis via b3

Gluconeogenesis via a1

Question 11

Endocrine Effects of Adrenergic R Agonists

Answer 11

Increased renin secretion via b1

Increased insulin secretion via b2

Question 12

Genitourinary Effects of Adrenergic R Agonists

Answer 12

Relaxation of detrussor and uterine SM via b2

Increased sphincter tone via a1
Ejaculation via a1

Question 13

Ophthal. Effects of Adrenergic R Agonists

Answer 13

Midriasis via a

–> decrease IO pressure

Question 14

Medical Uses

Anaphylactic Shock

Answer 14

Problem: general vasodilation, laryngeal oedema, bronchoconstriction

High dose Adrenaline (low dose would further decrease diastolic pressure)
High dose: a1, b1
Low dose: b1, b2 stimulation

Question 15

Medical Uses

Cardiac Arrest

Answer 15

Adrenaline

Question 16

Medical Uses

Acute HF/ Cardiogenic Shock

Answer 16

Dobutamine (b1>b2): prod. less tachy as opposed to
dopamine

Isoprenaline

Dopamine (D1, b1, a1): Progression of Rs with increasing
dose

Question 17

Medical Uses

Hypotension

Answer 17

Norepinephrine

acts on a1, a2, b1
Increase TPR, BP, HR, SV, CO
Potential reflex brady

Phenylephrine: a1

Question 18

Medical Uses

Bronchial Asthma

Answer 18

Selective b1 agonists
Terbutaline 
Salbutanol
Salmeterol
Formoterol

Question 19

Medical Uses

Obstetrics

Answer 19

Relaxation of uterus; prev premature labor

Terbutaline
Ritodrine

Question 20

Medical Uses

Topical

Answer 20

Against bleeding

Adrenaline

Question 21

Medical Uses

Nasal Congestion

Answer 21

Phenylephrine: a1

Metoxamine

Oxymetazoline

Naphazoline

Question 22

Medical Uses

Diagnostics

Answer 22

Induce Midriasis

Phenylephrine

Metoxamine