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PMP 101 Health, Disease and Patient > Pharmacoloogy- Drug targets ion channel > Flashcards

Pharmacoloogy- Drug targets ion channel Flashcards

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1
Q

Most abundant ions in the body

A
  • Sodium
  • Potassium
  • Calcium
  • Cations
  • Chloride
  • Phosphate
  • Fluoride
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2
Q

Key features of ion channels step 1

Selective transmembrane pore

A
  • Selective movement depending on charge & Size of the ions
  • Sodium channel will not permit potassium
    ions
  • K+ channels more selective to K+ than Na+
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3
Q

Key features of ion channels step 2

specific sensor for gating

A
  • Involved in the conformational change of the transmembrane pore allow ion movement
  • From closed to open conformation
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4
Q

Types of sensors or molecular switch

A

Membrane potential: Voltage-gated - changes membrane potential
neurotransmitter binding: Ligand gated and ligand binds (hormone) to open
Temp & stretch: mechanosensitive allows ion movement

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5
Q

Regulatory mechanisms Step 3

Regulatory mechanisms

A
  • Inactivation loop goes from open to inactive open in built
  • Abundance & location as post synaptic density
  • Modulation such as G proteins, 2nd
    messengers, protein kinases
  • Open inactive conformation stopping the imbalence
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6
Q

General structure of Voltage-Gated Ion Channel

A
  • 4 subunits align together to form one channel
  • 6- transmembrane helices
  • N-terminus and C-terminus intracellular
  • Partly hydropholbic and partly hydrophilic aminio acids
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7
Q

P-loop

A
  • Selectivity filter/molecular sieve
  • Align together to form a transmembrane pore
  • Makes pore for attachment
  • Combination of hydrophilic and hydrophobic
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8
Q

S4-Voltage sensor

A
  • Contains positively charged aminoacids
  • Can move up & down in response to changes in membrane potential acts as a sensor
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9
Q

Resting

Voltage sensing

A
  • S4 senses voltage difference depolarisation outside cell is positive as it is positioned intracellular
  • The changes in the membrane potential is detected by S4 and it moves up
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9
Q

Depolarisation

Voltage sensing

A
  • S4 senses voltage difference depolarisation outside cell is negative
  • Movement of S4 upwards allowing the opening which is positively charged
  • Causes sodium to enter
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10
Q

Major Drug targets

A
  • Ion channels
  • Receptors
  • Transporters
  • Enzyme
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11
Q

What are voltage gated ion channels influenced by

A
  • Other inorganic ions calcium channel influnced by nickel ion
  • Neurotoxins which are toxins from diffrent venoms
  • Sythetic drugs that block the channel
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12
Q

Ligand gated ion channels

A
  • Ligand gated binding site with 4 transmembrane helix per subunit with 5 of the subunits
  • N & C terminus are located extracellular
  • Ligand binding site closer to N-terminus and extracellular
  • S2 transmembrane domain forms pore lining
  • Alpha units contain Ach binding pocket - Such as nicotinic arch receptor
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13
Q

Neurotransmitters and channels

A

Acetylcholine - Nicotinic AchR
ATP - P2X
5-HT - 5HT-3
Glutamate - AMPA, NMDA, kainate
GABA - GABAA receptors

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14
Q

Ligand-gated cation channels

A
  • Cation channels - nicotinic Ach, glutamate, 5HT, P2X
  • Non-competitive antagonism
  • The memantine inhibitor blocks the sodium calcium channel
  • Causes depolarisation and excitation - fast response (stimulate)
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15
Q

Ligand-gated anion channels

A
  • Anion channel (Cl-): GABA&raquo_space; GABAA ICl&raquo_space; Hyperpolarisation&raquo_space; Inhibitory
  • Mediate fast postsynaptic inhibition in CNS
  • Modulation of GABA receptor drugs and alcohol
16
Q

Inactivation loop

A
  • Regulatory mechanism blocks the open ion channel pore to change conformation to open inactive
  • Ball chain mechanism give an activation time
17
Q

Lidocane effects on sodium channel

A
  • Local anasthetic drug prefers to act on open and inactive conformations
  • Use dependancy specific site (Open channels usually pain)
18
Q

Tetratadoxin effect on sodium channel

A
  • Targets all conformations blocks sodium channels preventing movement
19
Q

Use dependancy

A
  • Ion channels blockade depending on rate of action and potential discharge
  • Greater firing rate block those sodium channels
20
Q

Dugs that effect affinity for inactivated ion channels

A
  • Anti epileptic drugs and anti arrhythmic
  • Specific effects during large firing rate
21
Q

T type calcium channel

A
  • Small conductivity
  • Low sensitivity -70
  • Acts on pacemaker and causes contraction with neurotransmitter release
  • Gapapentin & pregablin inhibit T type calcium channels for epilepsy
22
Q

N type calicum channel

A
  • Intermediate sensitivity
  • The sensitivity level is -10mV
  • Targets the nerve particularly and releases neurotoxins
  • Conotoxin for severe chronic pain
  • Incartheal administration to block nerves and spinal cord
23
Q

L type calcium channel

A
  • Large level of conductance
  • High levels of conductivity
  • Localised on nerve
  • Longer lasting levels during cardiac muscle contraction
  • Amlodopine particularly acts on smooth muscle
  • verampril cardiac cells used for blood pressure and stroke
24
Q

Voltage gated potassium channels

A
  • Hyperpolarisation channel bringing action potental down (propogation)
25
Q

Intracellular ligand

A
  • Ca 2+ activated potassium channel
26
Q

G protien potassium modulation

A
  • Muscarinic cardic pacemaker cells
27
Q

Glutamate NMDA receptor

A
  • Ligand gated ion channel binds to the glutamate receptor causing sodium and calcium to enter
28
Q

Advantages of alosteric drugs

A
  • Fine tunes receptor function by intensifying hormone function
  • Clinically safer as there is enhanced selectivity and reduced liability for receptor tolarance

PMP 101 Health, Disease and Patient (64 decks)

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