Adrenoreceptor Drugs

Question 1

Somatic Nervous System
- # of neurons
- NT used
- name of receptor
- purpose

Answer 1

Somatic: voluntary control of skeletal muscle (conscious)

• SINGLE neuron pathway
• acetylcholine (Ach) released from neuron to the target muscle
• receptor of the receptor is the nicotinic receptor
• degraded ACH by the enzyme

Question 2

Autonomic Nervous system
- purpose
- number of neurons & where they arise from
- NTs used
- receptors

Answer 2

autonomic: automatic (involuntary) movements of smooth muscle, cardiac muscle & glands
two categories: sympathetic (fight or flight) or parasympathetic (rest and digest)

• both are a two neuron pathway with a pre-ganglionic and post ganglonic neuron

parasympathetic
- long pre-ganglionic neuron & short post-gang. neuron from the midbrain, brainstem and sacral region of the spinal cord
- ACH released at a nicotinic receptor at the ganglion
- then ACH released at a muscarinic receptor at the target organ
- ** musacrinic and nicotninc receptors = called cholenergic receptors**

sympathetic
- short pre-gang & long post-gang. arising from the T1-L1 spinal cord
- ACH released onto a nicotinic receptor at the ganglion
- norepinephrine released at the target organ onto a adrenergic receptor

Question 3

cholenergic receptor types?
anti-cholenergic drugs do what? cholenergic drugs do what?

Answer 3

cholenergic receptors: muscarinic and nicotinic receptors (accepting ACH)
- muscarnic: M1-M6 receptor subtypes
- nicotinic: no subtypes

anti-cholengeric drugs: will block the ACH from binding –> therefore stopping the PNS signal – becoming sympathomimmic drugs acting like the SNS ( urine retention, dry mouth, increased heart rate)

cholenergic drugs: will mimic the ACH binding to the receptors therefore mimicing the parasympathetic system

Question 4

adrenergic receptor types?
adrenergic receptor agonists? antagonists?
what is a catacholamine

Answer 4

adrenergic receptors
- beta (1 and 2)
- alpha (1 and 2)
- dopamine (1&2)

adrenergic receptor agonist: mimic the SNS –> therefore would have a catacholamine affect (beta agonists or alpha agonists)

adrenergic receptor antagonist: block the SNS –> mimic the PNS thus have a decreased catacholamine effect
(beta antagonists or alpha antagonists)

– catacholamines: NE, Epi, dopamine (epi = adrenaline)

Question 5

catacholamine effects at….
- the heart
- the lungs
- the blood vessels
- the CNS
- OTHER effects??? (urinary and GI)

Answer 5

at the heart: will have increased chronotropic (heart RATE via electrics) and increased inotropic (heat beat and force of muscles)

at lungs: will have a bronchodilator effect (hense why beta agonists work as asthma treatment)

at the blood vessels: if a low dose of a catacholamine – they will act at the Beta2 receptors: eliciting a vasoodialation effect but if high doses can act on Alpha1 and elicit a vasoconstriction effect

at the CNS: tremors, HA and anxiety in large amounts

other effects: urinary retection, decreased peristalsis, increased blood glucose

Question 6

how does epinephrine work at alpha and beta receptors of the andrenergic receptor sites? examples of clinical implications?

Answer 6

epinephrine: a beta and alpha agonist
– agonist: mimic a SNS response

think about an epi-pen: to treat anaphylaxis
think about IV epi: given in cardiogenic shock for CPR to initiate a normal heart rhythm

Question 7

how would an alpha-1 agonist work?
what are some examples?

side effects?

Answer 7

• agonist at alpha-1 : stimulate smooth muclse CONTRACTION therefore CONSTRICTION ALPHA 1 IN THE PERIPHERAL!!!!!

where do we see it used
- increase BP (by vasoconstriction) –> midodrine and phynlephrine
- reduce nasal congestion (by constrction) to stop the flood of inflammatory to the nose (pseudoephrine)
- reduce red eyes (constrict the vessel)

side effects: HYPERtension, excitability, restlessness, headache

Question 8

how would an alpha-2 agonist work?
what are some examples?

side effects?

Answer 8

alpha-2 agonist: receptors located in the brain and the brainstem –> thuse they block the outflow of signals (NE) to the rest of the body — overall decrease in SNS effect

• decrease BP –> clonidine and methlydopa for HTN
• stimulate the alpha-2 in the spinal cord –> deccreased muscle spasms
• stimulate alpha-2 in the eye –> decreased IOP

side effects: sedation, dry mouth, hypotension, bradycardia (anti SNS effects)

Question 9

how would a beta-1 agonist work?
examples?
side effects ?

Answer 9

beta 1: located within the heart myocardium trigger SNS –> trigger increased HR and Increased contractibility

used for…
- shock and decompensated heart failure: to increase cardiac output
- exercise tolerance tests (dobutamine) at high doses it will bind to alpha-1 receptors

side effects: tachycardia and arrythmias

Question 10

how would a beta-2 agonist work?
examples?
side effects?

Answer 10

beta 2 agonists: stimulate SNS type in the lungs –> trigger bronchodialation

• bronchodialation (albuterol)

side effects: excitmenet, nerouvsness, HA, tachycarida, tremor

Question 11

alpha-1antagonists and beta antagonists
use?
examples?

Answer 11

used majority for cardiac conditions (like lowering BP)

alpha1 antagonist: would dilate not constrict
beta antagonist: beta blockers for HTN to dialate