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Anesthesia Pharmacology > Membrane-Bound Receptors: Ligand gated ion channels and G-Protein Coupled Receptors > Flashcards

Membrane-Bound Receptors: Ligand gated ion channels and G-Protein Coupled Receptors Flashcards

1
Q

What is a Receptor:

A

A protein or group of proteins, usually embedded in the cell membrane, that allows the cell to collect information about its surroundings

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2
Q

What is a Ligand:

A

A chemical messenger (can be a small molecule or peptide) that binds and stabilizes a conformation of the receptor

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3
Q

Describe Conformational change:

A

change in the shape of a receptor that induces some downstream signal transduction

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4
Q

Properties of Receptors physiologically

A
  1. Receptors are normal points of control of physiologic processes.
  2. Under physiologic conditions, receptor function is regulated by molecules supplied by the body.
  3. Drugs can only mimic or block the body’s own regulatory molecules they will not give a cell new function
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5
Q

What are Agonists

A

drug combines with receptor to stimulate target organ

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6
Q

What are Antagonists

A

drug combines with receptor, but interferes with a naturally occurring agonist or an agonist drug

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7
Q

A ligand that binds to a receptor, thereby activating it is called an

A

agonist.

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8
Q

A ligand that binds to a receptor that prevents it from activating is called

A

an antagonist.

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9
Q

How does Orthosteric antagonist act?

A

They act on the main binding site of the receptor

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10
Q

How does Allosteric antagonist act?

A

They act on an accessory binding site of the receptor

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11
Q

How does Pore blocker act?

A

Physically obstructs the channel (ion channels)

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12
Q

Most receptors fluctuate between different natural conformations , some conformations are associated with pharmacologic activity and some are not. What are these activity?

A

Active
Partially active
Inactive

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13
Q

Drugs can activate or inactivate receptors by stabilizing a pharmacologically significant conformation by binding to the same site as the endogenous compound is called

A

orthosteric site

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14
Q

Drugs can activate or inactivate receptors by stabilizing a pharmacologically significant conformation by binding to an alternative site

A

allosteric site

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15
Q 
ligand gated ion channels:
Location
Effector site
Coupling
Examples
Structure
A

Location:
membrane

Effector site: Ion Channel

Coupling: Direct

Examples:
Nicotinic acetylcholine receptor, GABAa

Structure:
Oligomeric assembly of subunits surrounding central pore

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16
Q 
G protein-coupled receptors
Location
Effector site
Coupling
Examples
Structure
A

Location: Membrane

Effector site: Channel or enzyme

Coupling: G protein or arrenstin

Examples: Muscarinic acetylcholine receptor, adrenoreceptors

Structure: Monomeric or oligomeric assembly of subunits comprising seven transmembrane helices with intracellular G-protein- coupling domain

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17
Q

what is resting membrane potential

A

Resting membrane potential: Inside of the cell has an overall negative charge of ~-70 mV

18
Q

what is cell excitatory

A

Excitatory: means that the inside of the cell’s charge approaches 0 mV
Generally by letting positive ions into the cell

19
Q

What is cell inhibitory

A

Inhibitory: means that the inside of the cell’s charge becomes more negative
Generally by letting negative ions (mainly chloride) into of the cell

20
Q

Characteristics of ligand gated ion channels

A
  1. Fast transmission
  2. Composed of several subunits arranged around a central ion pore
    - - Agonist binding opens pore
  3. Major families:
    - - Cys-loop receptors: nicotinic acetylcholine receptor, glycine receptors, 5HT-3 receptor, etc.
    - - Ionotropic Glutamate Receptors: AMPA receptor, NMDA receptor, kainate receptor
21
Q

What are cys-loop receptors? Describe.

A
  1. Named for the loop formed by the disulfide bond between two cysteines near the N-terminus
  2. Made of five subunits arranged around a central pore
  3. Five types of subunits: α, β, γ, δ, ε
  4. Excitatory: Nicotinic acetylcholine receptors, serotonin receptors
  5. Inhibitory: Glycine and GABAA
22
Q

How does happen gating in cys-loop receptor

A

The second transmembrane domain of the α subunit generally obstructs the ion pore
Agonist binding changes the conformation, moving the obstruction and allowing ions to flow though

23
Q

Drugs that act on ligand-gated ion channels

A
  1. Cys-loop receptors
    - - Nicotinic acetylcholine receptors: Nicotine, Varenicline (Chantix)
    - - GABAA receptors: Ambien (zolpidem)Barbituates, benzodiazepines, alcohol
  2. Glutamate Receptors
    - - NMDA receptors: Ketamine
    - - AMPA receptors: Aniracetam (cognition-enhancer)
24
Q

cys-loop receptors includes excitatory and inhibitory receptors. List these receptors excitatory and inhibitory receptors.

A

Excitatory: Nicotinic acetylcholine receptors: Nicotine, Varenicline (Chantix)
Inhibitory: GABAa receptors: Ambien (zolpidem)Barbituates, benzodiazepines, alcohol

25
Q

List Glutamate Receptors

A
  1. NMDA receptors: Ketamine

2. AMPA receptors: Aniracetam (cognition-enhancer)

26
Q

Where do Nicotinic Acetylcholine Receptors exist?

A

Exist at the neuromuscular junction (NMJ) and in the CNS

27
Q

NMJ contain what subunits

A

contain a, β, δ, and γ subunits

28
Q

Neuronal nAChRs contain which subunits

A

Neuronal nAChRs contain only a and β subunits

29
Q

Excitatory Nicotinic Acetylcholine Receptors pass which ions

A

Pass Na+, K+, and some Ca++ ions

30
Q

Nicotinic Acetylcholine Receptors are composed of how many subunits

A

Composed of five subunits

31
Q

In the brain, nAChRs upregulate in response to chronic use of
hint (like smoking)

A

nicotine

32
Q

Ionotropic Glutamate Receptors are?

A
  1. AMPA receptors
  2. NMDA receptors
  3. Kainate receptors
33
Q

Excitatory Ionotropic Glutamate Receptors pass what ions?

A

Pass Na+ and K+ ions

NMDA receptors can also pass Ca++ ions

34
Q

Ionotropic Glutamate Receptors are composed of how many subunits

A

Composed of four subunits
Each subunit has four transmembrane domains
– Second TM domain forms the ion pore

35
Q

Each subunit of Ionotropic Glutamate Receptors has a binding site but not all binding sites are for glutamate

A

Each subunit of Ionotropic Glutamate Receptors has a binding site but not all binding sites are for glutamate

36
Q

NMDA receptor: two binding sites for glutamate, two binding sites for glycine
All four binding sites must be occupied for the channel to open

A

NMDA receptor: two binding sites for glutamate, two binding sites for glycine
All four binding sites must be occupied for the channel to open

37
Q

What is Long Term Potentiation (LTP):

A

Long Term Potentiation (LTP): the more often a neuron fires, the “stronger” the synapse gets
– Implicated in learning and memory

38
Q

At resting membrane potential, NMDA receptors are blocked by

A

Mg++
Magnesium block is voltage dependent
Depolarization of neuron relieves the block, allows NMDAR to open

39
Q

NMDARs pass Ca++, which activates Calmodulin Kinase II (CaMKII), which leads to AMPARs inserted into the synapse
More AMPARs = stronger synapse

NMDARs are “coincidence detectors

A

NMDARs pass Ca++, which activates Calmodulin Kinase II (CaMKII), which leads to AMPARs inserted into the synapse
More AMPARs = stronger synapse

NMDARs are “coincidence detectors

40
Q

What are the three main classes of G Protein-Coupled Receptors (GPCRs)

A
  1. Class A: adrenergic receptors, muscarinic acetylcholine receptors
  2. Class B: Parathyroid Hormone receptor
  3. Class C: metabotropic glutamate receptors, GABAB receptors
41
Q

G Protein-Coupled Receptors (GPCRs) are slower than ligand gated ion channels. What do they rely on for signaling

A

Slower signaling than ligand-gated ion channels
Rely on second messengers for signaling
~3% of our genome dedicated to GPCR coding

Anesthesia Pharmacology (7 decks)

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