02 - Drug receptor interactions (pharmacodynamics) Flashcards
Agonists…
activate receptors!
Antagonists…
block the action of an agonist
Benzodiazepines bind to the ( allosteric / orthosteric ) site of ( GABA A / GABA B / alpha-andrenergic) receptors
Allosteric site of GABA A
Benzodiazepines enhance the endogenous…
Effect of GABA (leading to greater hyperpolarisation, as more Cl- passes through the ion channel)
NSAIDs work by…
Enzyme inhibition
NSAIDs inhibit…
Cyclooxegenase
Drugs that mimic the endogenous process at a receptor are acting as…
Agonists
Drugs that inhibit the endogenous process at a receptor are acting as..
Antagonists
Histamine receptors have at least…
14 subtypes
Receptor subtypes may have both different specificities for agonists and differences in the…
Signal transduction pathway
The 4 major types of receptor are…
- Ligand-gated ion channel receptors
- G-Protein coupled receptors
- Enzyme (kinase) linked receptors
- Intracellular receptors
Which type of receptor acts the fastest?
Ligand-gated ion channel receptors (ionotropic)
All ionotropic channels have ( intracellular / extracellular ) ligand binding sites
Extracellular
G-Protein coupled receptors are slower than ligand-gated ion channel receptors, but have a…
Greater variety of responses
G-Protein coupled receptors are the most common…
Receptor type and drug target
G-Protein coupled receptors can either be (2)…
Direct (linked with an enzyme) or Indirect (triggers an ion channel)
adrenoreceptors are…
G-protein coupled receptors
Salbutamol is a drug which mimics the endogenous effects of which neurotransmitter on which receptors?
Epinephrine, (beta-2) andrenoreceptors
A trimeric G-protein is comprised of 3 subunits…
- alpha
- beta
- gamma
Which G-protein subunit has the most significant catalytic activity?
Alpha (which binds GTP)
Name the 3 main subtypes of alpha-subunit….
- Gs (activates adenyl cyclase, Ca2+ channels)
- Gi (inhibits adenyl cyclase, activates K+ channels)
- Gq (activates phospholipase C)
alpha 1 adrenoreceptor activates a G-protein with which alpha subunit type?
Gq -> activates phospholipase C
alpha 2 adrenoreceptor activates a G-protein with which alpha subunit type?
Gi -> inhibits adenyl cyclase and activates K+ channels
beta 1 and 2 adrenoreceptors activate a G-protein with which alpha subunit type?
Gs -> stimulates adenyl cyclase and activates Ca2+ channels
The stimulation of adenyl cyclase via activation of the beta 1 adrenoreceptor results in…
Accelerated heart rate
The stimulation of adenyl cyclase via activation of the beta 2 adrenoreceptor results in…
Broncodilation
Salbutamol is a beta 2 adrenoreceptor ( agonist / antagonist)
Agonist
leads to broncodilation, used to treat asthma symptoms
Atenalol is a beta 1 adrenoreceptor ( agonist / antagonist)
Antagonist
lowers heart rate
Kinase linked receptors feature a large extra cellular binding site linked to the intracellular domain by a…
Single membrane-spanning helix
Nuclear receptor binding sites are…
Intracellular
So the ligand must cross the cell membrane
Nuclear receptors are divided into (2)…
Class I and Class II
Class I nuclear receptors are found in the…
Cytoplasm
Class I nuclear receptors form…
Homodimers
Class I nuclear receptors bind…
Endocrine (Steroid, hormone) ligands
Class II nuclear receptors are found in the…
Nucleus
Class II nuclear receptors form…
Heterodimers
Class II nuclear receptors bind…
Lipid (fatty acid) ligands
Most receptor operated channels have…
a) a single binding site
b) two binding sites
c) multiple binding sites
d) no binding sites
c) multiple binding sites
Binding at one site can affect…
Binding at other sites
The orthosteric site is the…
Main binding site
Binding at the allosteric site can…
Modulate affinity at the orthosteric site (+/-) and bind antagonists
Receptors may also have areas known as…
Effector regions
Which also effect the receptor
