NICOTINIC RECEPTORS Flashcards
What type fo channel is the nAChrR CHANNEL
Cation channel
Nicotinic receptor activation leads to opening what kind of channel
Associated cation conducting ion channel
the nAChR channel usually primarily conducts what
Na+
What does the patch clamp technique allow for?
The study of both single and populations of receptor/channels in real time
Where are GABAa receptors located
endogenously located in the cortical neurones
What happens during oatch clamp technique regarding the research of GABAa receptors
Patch electrode approx 1cm in diameter is brought down onto the cell surface
Portoin of the cell membrane is drawn into the electrode to form a high resistance seal called a gigaseal
Membrane is subsequently ruptured and can be manipulated - cell exterior, imnterior and when volatge clamped the passage of current via GABAa receptors can be viewed
What are the different modes of patch clamp technique called?
Cell-attached
Whole-seal
Inside out
Outside out
What are advantages of the patch clamp technique- cell attched patch
- Can record the activity of single receptors
- The intracellular milieu is maintained (no wash-out of intracellular biochemistry)
-Control of the extracellular solution
What are the disadvantages of the patch clamp technique - cell attached patch
- Investigating different concentration os drugs eg. agonists is complex
- The agonist always present- issues with receptor desenstitisation
- No control of the intracellular content
-The resting membrane potential is not known
Advantages of PCT - whol cell voltage clamp
-Control of the intracellular and extracelluklar milleu
- Can record the population of receptors/ion channels
-Can introduce biochemical modulators (intracellularly) via the recording pipette
Disadvantgaes of PCT - whole cell voltage clamp
Biochemical washout of the intracellular mileu
Resolution - can rarely observe single receptor activity
Advantages of the PCT- Outside out patch
- Control of the intracellular and extracellular mileu
-Can change/control extracellular drufg (agonist) concentrations
Disadvantages of PCT- outside out
Biochemical washout of the intracellular mileu
Cannot easily chnage intracellular messengers e.g c-AMP
Advantages of PCT - inside out
Control of the intracellular and extracellular mileu
Can introduce biochemical modulators e.g c-AMP to the intracellular face
Disadvantages of PCT- insise out
Cannot easily change the concentration of agonist
Is the nAChR a selective or non-selective channel?
non-selective
Cloning of the nAChR has revealed what subunitsnin skelteal muscle and neuronal tissue?
SM- a1, b1, delta, gamma, E
Neuronal- a2-9, b2-4
Where abouts on the subunit does ACh bind
The subunit interfaces
What are therapeutic areas under investigation when loong at nAChRs
Alzheimers
Parkinsons
Schizophrenia
Attention deficit disorder
Pain- analgesia
Anxiety
Smoking cessation
What i sthe structure of the cys-loop receptor
Pentameric structure
What are the names of anion and cation conducting cys loop receptors
5HT3R - C
GABAaR- A
Glycine R - A
How would you study the functional properties of recombinant wild type and mutant receptors
The Canopus oocyte expression system with voltage clamp
Epithelial transfection system with whole-cell volatge-clamp and patch-clamp
How does the conformational chnage of the nAChR channel occur
Once agonist has bound, the agonist stabilises the loop C in a contracted form and loop C closes over the agonist
These small chnages in conformation of the ligand binding domain trigger the response
Extracellular and intracellular rings of negatuveky charged glutamate and aspartate residues influence what?
Cation conductance
