8 - Techniques in neuropharmacology Flashcards
How do we measure bioelectricity
Patch only
Small electrodes can record activity of
One neuron
Larger electrodes record the activity of
Several neurones
What is a microelectrode
h87lass electrode connects to amplifier
What cells are used for electrophysiology studies
Oocytes mainly
Some neurons
What are pros of using oocytes (2)
Express proteins well
Good for mutations
Technically easy
What are some cons of using oocytes (3)
Frog oocytes
Difficult to exchange drugs
Difficult to get good electrical control of the cell in neurons as only one electrode, noisy, hole in cell
What does patch clamp allows us to do
Control the voltage of most mammalian neurons or ‘clamp’ the voltage
What does the amplified of the patch clamp do
Maintains a membrane potential and measures the currents require dot maintain it
What is an upward current
Positive ions leaving
Negative ions entering
What does a current clamp measure
Change in membrane potential caused by the applied current
What does a voltage clamp measure
The transmembrane current required to maintain the voltage
What is the pro of current clamping
Mimics current produced by a synaptic output
What is the pro of voltage clamping
Control voltage to limit the changing variables
What does patch clamping allow us to do
Low noise
can measure the current flow through 1 channel
What does whole-cell patch clamping allow us to do
Study ion channels of:
- isolated cells
- cell culture
- cells in brain slices or in vivo
What affects the size of the post-synaptic current
1) How much glutamate is released
2) How many post-synaptic AMPA receptors
3) Location of AMPA receptors
4) Phosphorylation state of AMPA receptors
5) Voltage of post-synaptic cell
6) Ions inside and outside the cell
What are some cons of patch clamping
1) Quite hard
2) Can be expensive
3) Not suitable fo rall cells
4) One cell at a time
5) You lose things when you prepare the cells
What is optogenetics used for
Selective activation of sub-population neurons
Fantastic temporal control
What is immunohistochemistry
Identification of specific tissue components by means of a specific antigen reaction tagged with a visible label
What does immunohistochemistry allow
Localisation of the antigen within a cell or tissue
What is an example of an enzyme linked secondary
Biotin bound to high affinity Avidin
Why do secondaries have high sensitivity
Reaction is amplified
What are some pros of fluorescent secondaries
1) High structural resolution possible
2) Quantification
3) Versatile
4) Multiple labelling
5) Live cells
