Adrenergics

Question 1

Neurotransmitters of the ANS

Answer 1

Acetylcholine, norepinephrine, epinephrine

Question 2

Receptors of the ANS

Answer 2

Nicotinic AChR, muscarinic AChR, alpha1 adrenergic, alpha2 adrenergic, beta1 adrenergic, beta2 adrenergic

Question 3

Alpha1 adrenergic receptors

Answer 3

Gq/Gi/Go mediators, present in vascular (contraction), genitourinary (contraction), intestinal (relaxation) smooth muscle, heart (increased excitability), and liver (glycogenolysis/gluconeogenesis)

Question 4

Alpha2 adrenergic receptors

Answer 4

Gi/Go mediators, present in pancreatic beta cells (decreases insulin secretion), platelets (aggregation), nerves (decrease NE release), vascular smooth muscle (contraction)

Question 5

Beta1 adrenergic receptors

Answer 5

Gs mediators, present in heart (increased AV conduction velocity, increased rate and force of contraction), renal juxtaglomerular cells (increased renin secretion)

Question 6

Beta2 adrenergic receptors

Answer 6

Gs mediators, present in smooth muscle (relaxation), liver (glycogenolysis/gluconeogenesis), skeletal muscle (glycogenolysis and potassium uptake)

Question 7

Major adrenergic receptors in the heart

Answer 7

Beta1, alpha1

Question 8

Major adrenergic receptors in the blood vessels

Answer 8

Alpha1, alpha2

Question 9

Major adrenergic receptors in the lungs

Answer 9

Beta2

Question 10

Effect of beta1 receptor stimulation on heart

Answer 10

Results in increased cardiac contracility and heart rate

Question 11

Effect of beta2 receptor stimulation in bronchial smooth muscle

Answer 11

Results in dilation of the airways, beta2 agonists alleviate asthma symptoms

Question 12

Nonselective beta antagonists

Answer 12

Propranolol, pindolol, nadolol, timolol, carteolol, all beta1 = beta2 selectivity, available in sustained release preparations for long-term disease management

Question 13

Propanolol

Answer 13

Prototype beta-blocking drug, low, dose-dependent bioavailability

Question 14

Timolol

Answer 14

Used for glaucoma

Question 15

Beta1 selective antagonists

Answer 15

Metaprolol, atenolol, acebutalol, nebivolol, selective for beta1 receptors, preferred in patients with diabetes mellitus and asthma

Question 16

Nebivolol

Answer 16

Highly selective for beta1 and exhibits additional effects of vasodilation

Question 17

Action of alpha1 antagonists

Answer 17

NE stimulates alpha1 receptors on vascular smooth muscle to contract, antagonists result in vasodilation, lower blood pressure, alpha1 antagonism also reduces urethral tone and alleviates bladder outlet obstruction in benign prostatic hyperplasia

Question 18

Prazosin

Answer 18

Highly selective alpha1 antagonist, effective for management of hypertension, dilates arteries and veins, relative absence of tachycardia

Question 19

Phenoxybenzamine

Answer 19

Irreversible blockage of alpha receptors, slightly selective for alpha1 over alpha2, may increase cardiac output (reflex tachycardia due to baroreceptors), side effects: nasal stuffiness, orthostatic hypotension, tachycardia, inhibition of ejaculation

Question 20

Alpha2 agonists

Answer 20

Stimulation of alpha2 autoreceptors centrally inhibits NE release and sympathetic output

Question 21

Clonidine and guanabenz

Answer 21

Alpha2 adrenergic agonists used for hypertension, inhibit sympathetic outflow from CNS, decreases heart rate, contracility, vasomotor tone

Question 22

Carvedilol

Answer 22

Mixed alpha-beta antagonist, more potent at beta receptors than alpha1, effective for treatment of chronic heart failure with decreased systolic function

Question 23

Epinephrine

Answer 23

Hormone, higher affinity for beta receptors (beta2) compared to alpha receptors, increases muscular contraction and heart rate, decreases total peripheral vascular resistance, increases blood flow to muscles, dilates airways

Question 24

Norepinephrine

Answer 24

Higher affinity for alpha receptors than beta receptors, increases total peripheral vascular resistance, increases muscular contraction of the heart

Question 25

Beta-adrenergic receptors

Answer 25

Coupled to G2, increase cAMP, cellular response depends on type of tissue and isoform of receptor

Question 26

D1 and D5 dopaminergic receptors

Answer 26

Coupled to Gs with increase in cAMP, D1 are expressed in kidneys, mesentery, coronary arteries, cause relaxation in vascular smooth muscles (vasodilation)

Question 27

D2, D3, D4 dopaminergic receptors

Answer 27

Coupled to Gi, decrease cAMP, increase potassium conductance, decrease calcium influx

Question 28

Acebutolol

Answer 28

Partial beta1 agonist, no effect on B2, used for management of hypertension, may produce less bradycardia

Question 29

Action of alpha1 adrenergic receptor

Answer 29

Gq, stimulates phospholipase C, leads to increased IP3 and DAG, IP3 causes release of calcium for muscle contraction, DAG activates PKC, phosphorylates proteins

Question 30

Action of alpha2 adrenergic receptor

Answer 30

Gi, inhibits adenylyl cyclase, decreases cAMP

Question 31

Terazosin

Answer 31

Alpha1 selective antagonist, used for treatment of hypertension, urinary complications associated with benign prostatic hyperplasia (BPH)

Question 32

Doxazosin

Answer 32

Treatment of hypertension and BPH, long plasma half life

Question 33

Tamsulosin

Answer 33

More selective for alpha1a and alpha1d receptors, effective for BPH, less orthostatic hypertension

Question 34

Labetalol

Answer 34

Alpha and beta antagonist effects (slightly selective for alpha1), treatment of hypertensive emergencies, pregnancy inducing high blood pressure