Receptor theory Flashcards

1
Q

Sir Henry Hallet Dale

A

-1875-1968
-pharmacologist + physiologist
-discovered acetylcholine

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2
Q

James Black

A

-discovered H2 antagonist, cimetidine (suppresses the formation of gastric acid and is used to fight ulcers)
-nobel prize in 1998

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3
Q

Old waiting chair occupancy model

A

-developed by A.J Clark
Chair analogy
-chairs= receptors
-people= agonist
-people sit and get off of chairs completely randomly, such as agonists bind and unbind randomly
-1 to 1 exchange, 1 agonist occupies 1 receptor to illicit 1 response
-the more receptors that are occupied, the more response
-MAXIMUM RESPONSE is when all receptors are occupied

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4
Q

A. J Clark

A

provided the first quantitative study of antagonism of acetylcholine by atropine

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5
Q

Agonist

A

-usually something in your body
-a drug or a molecule or ligand etc that binds to a receptor to produce a response

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6
Q

Exogenous molecules (agonist)

A

try to mimic that natural endogenous molecule
-produces the intended response

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7
Q

Antagonist

A

(safer term to use is inhibitor, unless exact mechanism is known)
-a drug or molecule or ligand etc, that binds to a receptor to interfere with an agonists response
-can either stop the response or lessen the response

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8
Q

Dose

A

concentration of drug (molecule), usually measured in moles

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9
Q

Response

A

The observable change associated with variation in agonist concentration: can be contraction, secretion, inhibition, etc

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10
Q

Effect

A

synonymous with response: drug effect produces response

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11
Q

Log(agonist)

A

useful measurement tool because very large magnitude differences in concentrations can be represented on the X-axis with small, simple numbers

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12
Q

%inhibition

A

A type of response whereby the thing being measured is how much an effect that would usually be present is inhibited in the presence of an agonist

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13
Q

Potency

A

The strength needed for a drug to elicit a response
Eg; the MORE potent the drug the LESS of it is needed to create a response

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14
Q

Efficacy

A

-The response of a drug
-the maximum response of a drug means that even with an increase of the drug, the response cannot decrease
Eg; “doability” the more efficacious, the more drug can DO its job and get a RESPONSE

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15
Q

Affinity

A

How attracted the drug and receptor are to each other
Eg; “stickability” the more affinity, the greater they can stick together

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16
Q

EC50

A

A quantitative measure that indicates how much (concentration) of a substance (e.g. drug) is needed to produce, in vitro, 50% of the maximal response

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17
Q

kD

A

Can be extrapolated from EC50- big pharmacological importance
kD= kON/kOFF

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18
Q

IC50

A

A quantitative measure that indicates how much of a particular inhibitory substance (e.g. drug) is needed to inhibit, in vitro, a response by 50%.

(would be an antagonist)

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19
Q

TDLR EC50

A

The concentration of the drug needed to produce 50% of its maximum response.

20
Q

Competitive antagonism

A

-There is only a shift to the RIGHT and NO change in maximum response
-with this type of antagonism, you can still get back to the maximum response with an increase in the agonist (drug)

(CAUTION: it is hard to prove - you need to know the exact mechanism that causes this shift. If you want to argue it is a competitive antagonist use surmountable antagonist)

21
Q

Irreversible antagonism

A

-There is a DOWNWARDS shift and a CHANGE in MAXIMUM RESPONSE
-with this type of antagonism, with the same dose of agonist, or increase in agonist, you can NO LONGER achieve the same maximum response. Thus, its IRREVERSIBLE

(CAUTION: it’s hard to prove, you need to know the exact mechanism causes this shift. So if you want to argue it without saying it, use INSURMOUNTABLE antagonism - COVALENTLY BONDED)

22
Q

Daniel Bovet

A

Discovered H1 antagonist and won noble prize in 1957

23
Q

Stochastic nature of the body

A

-it is completely random which molecule binds to which receptor
-at any moment there will be a population of binding sites
-which sites are bound will depend on the number of molecules that preferentially bind to that site
-if the molecule has diffused away from that site it becomes available for other molecules - similar (agonist) or dissimilar (antagonist) to bind to the previous receptor

24
Q

Equilibrium

A

forward reaction = the reverse reaction

25
kON = kOFF
When the rate of forming a new signal-receptor complex= the rate at which an existing signal-receptor complex dissociates
26
kON
how fast a molecule gets to receptor
27
kOFF
how long the molecules stay on receptors
28
neurotransmitters
-high kD (fast off rates) -low affinity
29
hormones
-low kD (slow off rates) -HIGH affinity
30
The law of mass action
IT'S JUST EQUILIBRIUM
31
Four categories of membrane receptors
-receptor channel -G protein-coupled receptor -receptor-enzyme -integrin-receptor
32
Catalytic receptor
-receptor-enzyme -integrin-receptor
33
Receptor channel
Ligand binding opens or closes the channel
34
G protein-coupled receptor
Ligand binding to a G protein-coupled receptor opens an ion channel or alters enzyme activity
35
Receptor-enzyme
Ligand binding to a receptor-enzyme activates an intracellular enzyme
36
Integrin receptor
Ligand binding to the intern receptors alters enzymes or the cytoskeleton
37
Signal transduction pathways
38
Mast Zellen
swollen or fat; coined by Paul Ehrlich
39
Ubiquitous
everywhere (mast cells are ubiquitous in the body)
40
Organ bath
Ex vivo, measures force transacted by tissue sample Example: testing how much a sample of intestinal tissue contracts or relaxes in the presence of loperamide (Immodium)
41
Ussing chamber
Ex vivo, measures molecule movement across a membrane Example: testing how much acid a sample of epithelial parietal tissue secretes in the presence of histamine
42
SEM microscope
Gives 3 dimensional images of lower resolution
43
TEM microscope
Gives 2 dimensional images of higher resolution
44
Southern blot identifies
DNA
45
Northern blot identifies
RNA