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M.Phil. Preparatory Flashcards > Pharmacodynamics2 > Flashcards

Pharmacodynamics2 Flashcards

1
Q

Drugs impart new functions within the body? If true then justify!

A

No they only alter the pace of activity .

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2
Q

Why do most drugs not be classed as stimulants?

A

Many drugs have agonist effect on one cell and antagonistic on another type of cell.

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3
Q

What are the basic types of drug action?

A

Stimulation, depression, irritation, replacement, and cytotoxic action.

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4
Q

Drugs most commonly interact with what kind of biomolecule?

A

Proteins

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5
Q

An antagonist has no effect of it’s own?

A

Yes, that true!

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6
Q

What antagonizes the full effect of agonist?

A

Partial agonist

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7
Q

What is affinity and intrinsic activity?

A

Affinity is the ability of drug to bind a receptor whereas intrinsic activity is the ability to induce functional change in the receptor.

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8
Q

What binds a receptor but does not activates it?

A

Competitive antagonist

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9
Q

Functional response by a receptor is a function of?

A

The conformational change induced by the ligand.

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10
Q

Explain which of the following has intrinsic activity or affinity?

A

Agonist has both, competitive agonist has affinity but no IF, Inverse agonist has both but IF is reverse, partial agonist has both.

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11
Q

True or false? Partial agonists can have higher affinity than full agonist?

A

Yes, but functional induction is inferior than full agonist.

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12
Q

Receptors exist in multiple inactive and active conformations?

A

True

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13
Q

GDP is bound to which of the three trimeric proteins of g protein?

A

Alpha subunit during the inactive state.

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14
Q

What happens when the Gprotein is activated?

A

Alpha-GDP complex is displaced into Alpha-GTP complex and then disassembles from the other two subunits to activate or deactivate the effector.

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15
Q

What is the role of beta and gamma subunits at high receptor activation?

A

It desensitizes the GPCR by activating the K+ channels whereas deactivating the Na+ channels.

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16
Q

How does the alpha subunit returns to its trimeric form?

A

It has GTPase activity due to which the GTP is hydrolyzed to GDP and the protein then returns to its resting phase.

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17
Q

What regulates the active Alpha-GTP complex?

A

RGS

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18
Q

What ends the activity of cAMP?

A

PDEs (phosphodiesterase) hydrolyzes it to 5-AMP

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19
Q

What’s the alternative secondary messenger to cAMP?

A

cGMP

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20
Q

What’s the primary messenger in GPCR?

A

Ligand

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21
Q

What are the two forms of cGMP?

A

Cytosolic and membrane bound regulated by NO and enzyme respectively not GPCR.

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22
Q

What are the steps of GPCR?

A
  1. Agonist binding
  2. Gprotein and receptor coupling
  3. aGDP to aGTP
  4. Disassociation of trimeric units from the receptor.
  5. Binding to enzyme or ion channel (PKA or Na+ channel, etc.)
  6. Effect depends on Gprotein nature (Gs, Gi, Gq, G0 etc.)
    Termination
  7. GTpase activity causes the hydrolyses of aGTP to aGDP, which then binds the two other subunits.
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23
Q

What’s the main difference between cAMP and Phospholipase pathways

A

The secondary messengers in Phospholipase is IP3 and DAG one assists in ca+ depooling and the other along with ca+ helps to activate protein kinase c, In cAMP the sec messenger is cAMP and enzyme is Adenylyl cyclase whereas in Phospholipase pathway the enzyme involved is PLc

24
Q

What are metabotropic and inotropic receptors?

A

GPCR is metabotropic whereas ligand gated Ion channels inotropic

25
Q

What are the secondary messengers you’ve studied?

A

cAMP, cGMP, NO, IP3, and DAG, etc

26
Q

What are the steps of ligand ion channel receptors

A

B-O-F-H/D-R

27
Q

What is the step of enzyme linked receptor?

A

Binding-receptor dimerization-Kinase activity stimulation-signaling pathway-Gene transcription- tissue response

28
Q

How is a receptor regulated?

A
  1. Receptor masking
  2. Desensitization of the receptor
29
Q

Receptor also amplifies signal, True or False?

A

True

30
Q

What is unusual about JAK-STAT receptors?

A

It doesn’t contains an intrinsic catalytic domain.

31
Q

What are the steps of JAK-STAT enzyme receptors

A

Agonist binding, Dimerization of receptor, JAK binding, Receptor Tyrosine phosphorylation, STAT binding, STAT(dimeric form) transcription activation.

32
Q

What are the examples of Enzyme linked receptors

A

Tyrosine kinase receptors for insulin, and epidermal growth factor

33
Q

What is the difference between transmembrane enzyme linked and non enzyme linked receptors?

A

Intrinsic catalytic domain

34
Q

What is an example of non intrinsic catalytic domain based receptor?

A

JAK-STAT receptor for gene transcription

35
Q

What is an example of ionic channel receptor?

A

Nicotinic acetylcholine receptors, and GABA receptors in CNS

36
Q

What are examples of GPCRs?

A

Alpha2 and beta adrenergic receptors, Muscarinic receptor

37
Q

What is the mechanism of DNA regulating receptors?

A

Agonist binds, restricting protein detaches, Receptor dimerizes (DNA binding domain config), complex moves to the nucleus, associates with other complexes, binds DNA and regulates its transcription.

38
Q

What’s the full form of IP3?

A

Inositol 1,4,5-triphosphate

39
Q

What is the full form of DAG?

A

Diacylglycerol

40
Q

What’s the importance of Ca+ ions in Cell signaling?

A

It facilitates the activation of certain functional enzymes, might bind with other effector systems, present inside the ER or membrane bound pools, combines with calmodulin to activate myosin light chain.

41
Q

What’s the difference between DAG and IP3

A

IP3 fluxes out into the cytosol whereas DAG remains in the membrane. IP3 helps in releasing Ca+ ions from ER whereas DAG activates the PLC enzyme with the help of Ca+ ions to generate the effector response.

42
Q

True or False? cGMP has one Guanylyl cyclase enzyme?

A

No it has two types, one is membrane bound and the other at the intrinsic end. The former is regulated by an enzyme linked receptor whereas the latter is activated by NO.

43
Q

What is the precursor molecule of IP3

A

PIP2 (phosphatidylinositol 4,5-bisphosphate)

44
Q

What’s the precursor of DAG?

A

TAG (Triacylglycerol)

45
Q

What is the nature of DAG and IP3 formation?

A

Membrane lipid is the precursor for both, enzymatic hydrolysis based process produces the two messengers.

46
Q

What are the three pathways through which GPCR regulates the cell process?

A
  1. cAMP/cGMP pathway
  2. DAG/IP3 pathway
  3. Ionic channel
47
Q

What is the name of the enzyme in cAMP/cGMP pathway?

A

Adenylyl Cyclase and Guanylyl Cyclase

48
Q

What’s the name of the enzyme in DAG/IP3 pathway?

A

Phospholipase C or PLC

49
Q

True or false? Ionic channels need a secondary messenger intervention for their process?

A

No they don’t. Depending upon the specific type of G-protein it activates or deactivates the ionic channels.

50
Q

What is the significance of Ca+ and K+ ionic channels?

A

Ca+ activation usually facilitates the processes that cause an effector response whereas, K+ seems to work oppositely.

51
Q

Explain the nature of each of the types of these G proteins; Gs, Gi, G0, Gq

A

Gs = AC and Ca2+ activation
Gi = AC and Ca2+ deactivation, K+ channel activation
G0 = Ca2+ channel deactivation

52
Q

What is agonist pleotropy?

A

Coupling of more than one type of G protein for instance the coupling of Gi and G0 in muscarinic M2 receptors

53
Q

What is the relationship between Ca2+ and K+ ions?

A

Mostly work antagonistically, Ca2+ causes depolarization whereas K+ results in repolarization.

54
Q

What is the 3rd messenger in DAG/IP3 pathway?

A

Ca2+ ions

55
Q

What is the nature of JAK?

A

It’s a protein kinase that binds the receptor to phosphorylate it for STAT molecule.

56
Q

What is the full form of STAT?

A

Signal transducer and activator of transcription

57
Q

What is the location of JAK and STAT?

A

JAK is bound to the receptor and STAT is in the cytosol

M.Phil. Preparatory Flashcards (22 decks)

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