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Pathophys/Pharm > Drug Receptors > Flashcards

Drug Receptors Flashcards

1
Q

What does an agonist do?

A

Produces/promotes a similar response to the intended chemical

(acts like the ligand on the target receptor)

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2
Q

What does an antagonist do?

A

Blocks the effect of the ligand on the target receptor

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3
Q

How can two different drugs have the same result for a patient? Example: pt with COPD and pt with Asthma, both have constricted bronchioles but two different drugs could treat them.

A

One drug (sympathetic beta2 activation) causes bronchial dilation and one drug (parasympathetic m3 antagonism) blocks constriction….both lead to the same end result of opening bronchioles

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4
Q

What does pharmacology study?

A

At the receptor level, what is the mechanism of action?
Ex: Beta 2 agonist, M3 antagonist

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5
Q

What does pharmacodynamics (PD) study?

A

What is the physiological effect of the drug on the body?
Ex: dilates bronchial tubes, increases HR

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6
Q

What does pharmacokinetics (PK) study?

A

What does the body do to the drug?
ADME

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7
Q

What does pharmacotherapy study?

A

Choosing which drug is best for the pt

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8
Q

What does a modulator drug do?

A

Has both agonist and antagonist effects

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9
Q

What channels have quick acting effects?

A

Ligand-gated ion channels and G protein-coupled receptors

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10
Q

5 protein subunits form the _____ of a ion channel

A

Pore

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11
Q

T/F a specific ion channel let ions flow in and out of a cell

A

False. Ion channels either allow ions into a cell OR out of a cell (one way flow)

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12
Q

How are voltage gated ion channels activated?

A

By a charge, activation of one leads to activation of the next one and so on

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13
Q

T/F Voltage gated ion channels are specific for one ion

A

True

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14
Q

Voltage gated ion channels do not require a _____

A

Ligand

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15
Q

Where are voltage-gated ion channels found?

A

On nerves

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16
Q

What is an example of a drug that uses a voltage-gated channel?

A

Lidocaine (antagonist) it blocks voltage-gated Na+ receptors which blocks Na+ permeability

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17
Q

How do ligand gated ion channels work?

A

A endogenous ligand binds to a subunit of the pore which causes the permeability of the channel and allows ions to flow through it

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18
Q

What is an example of a ligand gated ion channel?

A

Nicotinic Acetylcholine Receptor. At rest, the channel is closed and no ions flow through. Acetylcholine binds to 2 of the subunits (alpha) which opens the channel and Na+ flows through (intracellularly which is down the concentration gradient) and finally initiates a muscle contraction.

19
Q

Why do people respond to drugs in different ways?

A

We all have the same subunits that make up the pores of ion channels, but there are different subtypes of the subunits which we all differ in.
Short answer: we have different receptor subtypes

20
Q

What is Dr. Stremski’s favorite ion channel?

A

GABA-A (binds to subunit which allows Cl- influx)

21
Q

What does the 5HT3 Ligand-gated channel responsible for?

A

When serotonin binds to the 5HT3 receptor, the channel opens leading to an influx of Na and K into neurons –> this causes you to puke.
*5HT-3 Anti-emetic drugs are antagonist, they bind to the receptor and block serotonin from binding = no more puking!

22
Q

What is the structure of a G-Protein Coupled Receptor? (GCPR)

A
  • One long peptide chain
  • Wraps in and out of the membrane 7 times
  • Amino Terminal = extracellular
  • Carboxyl Terminal = intracellular
23
Q

Where does a ligand bind in a G-protein coupled receptor?

A

Active site in the transmembrane region

24
Q

What do G-proteins interact with?

A

Cytoplasmic region

25
Q

What is an example of a GCPR?

A

All sympathetic NS receptors are GPCR (classified as Alpha and Beta)

26
Q

Do GPCR require a ligand to be activated?

A

Yes

27
Q

What are the three components to G-protein coupled receptors?

A
  1. Ligand binds to receptor
  2. Receptor triggers the activation of a G-protein
  3. G-protein changes the activity of an effector element (usually an enzyme or ion channel)
28
Q

What is the role of adenyl cyclase?

A

Catalyzes the reaction of ATP –> cAMP

(less adenyl cyclase, less cAMP)

29
Q

Migraine example (migraines occur because of vasodilation, so to reverse a migraine, you want vasoconstriction)

A

5HT-1B and 5HT-1D receptors are found in CNS and on blood vessels. Coupled to inhibitory Gi, the 5HT-1 receptors have an inhibitory effect on adenyl cyclase and reduce intra-cellular cAMP. cAMP mediates smooth muscle relaxation of large cerebral arteries –> inhibition of cAMP leads to vasoconstriction = no more migraine!

(in short: 5HT-1B/1D inhibit adenyl cyclase, which causes a decrease in cAMP which then causes vasoconstriction of cerebral blood vessels which gets rid of a migraine)

30
Q

Which receptor is ionotropic and which is metabotropic?

A

Ion channels = ionotropic
G-coupled protein channels = metabotropic (indirectly linked to ion channels through signal transduction pathways)

31
Q

Ionotropic Receptors: 5 units form a _____ which alters ______

A

Pore, Permeability

32
Q

Metabotropic Receptors: combined to ______ which cause synthesis of ______

A

G-proteins, activators

33
Q

What is the structure of Tyrosine Kinase Receptor (TKR)?

A
  1. Extracellular hormone binding site
  2. Cytoplasmic enzyme domaine that has multiple tyrosine AA
34
Q

Explain how a TKR is activated and the cellular response

A
  1. Two inactive monomers that contain multiple tyrosine AA’s
  2. A ligand binds to the signal-binding site (extracellular) and the two monomers form a dimer (it is not activated)
  3. ATP donates a phosphate to each tyrosine
  4. The phosphorylated tyrosines activate kinases which causes a cellular response (DNA Transcription)
35
Q

In what ways can a Tyrosine Kinase Receptor’s activity be inhibited?

A
  1. Something can bind in place of the ligand
  2. Something can alter the effects of the kinase
36
Q

How do TKRs play a roll in cancer?

A
  • EGF ligand enhances cell growth and division
  • We stop cancer by blocking cell growth and division
  • Drug is an antagonist to EGF - the drug binds on the receptor so EGF cannot
37
Q

A ligand has to be _____-soluble to act on an intracellular receptor

A

Lipid

38
Q

Where specifically are intracellular receptors found?

A

Cytoplasm

39
Q

Is the effect of intracellular receptors immediate or delayed?

A

Delayed because time is required to copy DNA and make new proteins

40
Q

How long can the effects of intracellular receptors last?

A

Hours to days (even after the drug is all gone because new proteins are active for days after synthesis and slow turnover of enzymes and proteins)

41
Q

What are examples of biological lipid-soluble ligands?

A

-Steroids (corticosteroids, sex steroids, vitamin D) and thyroid hormone

42
Q

What happens when a intracellular receptor is activated?

A

Transcription and translation

43
Q

Overview of all four receptors

A
44
Q

What do glucocorticoids do?

A

They suppress the inflammatory response (antagonist?)

Occurs via DNA transcription

  • Decrease transcription of lipid soluble and protein based inflammatory mediators
  • Are cytotoxic to lymphocytes (B and T)
  • Inhibit function of tissue macrophage in antigen processing

Pathophys/Pharm (9 decks)

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