L1 - Intro to Ion Channels Flashcards
What do gated ion channels have?
a component that is able to block the pore to prevent flow
Conductive channel =
ions/current flows
Non-Conductive channel =
no flow/current
Ion Channel Classification
Selectivity
whats the main ion that flows through
Ion Channel Classification:
Gating
what makes them open or close
Ion Channel Classification:
Regulation
What regulates the channel
K.ir Potassium Channels
have 4 subunits of transmembrane channels with no receptor site
K.v Potassium Channels
has 24 transmembrane domains and 2 beta subunits
Na.v / Ca.v channels
have 24 transmembrane domains and 2 beta subunits
CFTR Cl-
has 12 transmembrane domains
Ach Channels
are ligand gated nicotinic ion channels
What does the Patch Clamp technique do?
measures ion channel function
How does the patch clamp technoque work?
1 - A glass pipette filled with salt solution and an electrode connected is touched onto the cell membrane.
2- The pipette is sucked and the membrane seals to the pipette
3 - ion channels can now be measured via the electrode
What do whole cell recordings measure (patch clamp)
the current along the whole membrane of the cell
What do single channel recordings measure (patch clamp)
the curent along a single section of the membrane
What are the 3 things the patch clamp technique recordings allow for?
1 - Identification - what ion channels are present
2 - Regulation - the type of gating
3 - Physiological function - evaluation of the ion channels function
What is the equation for current recordings?
I = N.Po.g (Vm -Ei)
total current carried by poulation channles on the membrane = number of channels x open probability x single channel conductance x (membrane potential - nerst potential)
What is open probability?
A measure of how often the channels are open
What is single channel conductance?
A measure of how many ions move through the pore
Ion Channel Function …
When open, drive the membrane potential towards its nerst value
What molecule is a potassium channel blocker?
Barium
What molecule is a Sodium channel blocker?
Tetrodotoxin
What are some syptoms of FHEIG?
Bi-temporal narrowing
Hypertrichosis (hairy)
Thin upper lip
Long bushy eyebrows
Delayed development of intellectual ability and motor skills.
Suseptibility to Seizures
What are some syptoms of FHEIG?
Bi-temporal narrowing
Hypertrichosis (hairy)
Thin upper lip
Long bushy eyebrows
Delayed development of intellectual ability and motor skills.
Suseptibility to seizures
EEG anomalies
What causes FHEIG?
Mutation in KCNK-4 (K+ channel)
What kind of mutation is the KCNK-4?
Gain of function
What areas are the KCNK-4 channels mainly expressed?
PNS & CNS
The mutated KCNK-4 causes …
high extracellular K+ levels
