Transporters/Channels Flashcards
What does the patch-clamp technique allow?
It allows characterization of single channels. It records microscopic currents and provided the first direct evidence for single channels. It also allows for identification of toxins on specific channels.
From the patch clamp experiment what did they find between microscopic ionic currents and macroscopic ionic current?
They found them to be the same. The voltage clamp and patch clamp had similar results.
Describe the properties of Na+ channels:
opening is voltage-dependent. Open near beginning of depolarization pulse. Inactivate. Current reverses at Ena. TTX blocks the channels
Describe the properties of K+ channels:
Opening is voltage-dependent. They open later. Many do not inactivate, they just close at a specific voltage. TEA (or Cs+) blocks them.
Voltage gated ion channels allow how many types of ions to flow through? What about ligand gated?
Voltage - 1 (there are exceptions)
Ligand - two or more types (typically)
There is a large diversity of K+ channels, why is this?
It allows for differences in activation, gating and inactivation.
What is known about the CNS and channel properties?
The ion channels are encoded by large and diverse families of homologous genes. They differ widely in cellular expression and subcellular localization. They contribute to complex electrical response.
What is the diversity of ion channels in the CNS key to?
They are key to developing new therapeutics for CNS disorders
Channelopathies are genetic diseases resulting from mutations in channels what are some voltage gated Ca+ channelopathies?
Congenital stationary night blindness
Familial hemiplegic migraine
Episodic ataxia type 2
What are some Na+ channelopathies?
Generalized epilepsy with febrile seizures
What are some K+ channelopathies?
Benign familial neonatal convulsion
What do mechanosensitive ion channels sense?
Touch, hearing, osmoregulation, neuromuscular stretch
What do heat sensitive ion channels detect?
Pain, temperature, inflammatory response
There are a bunch of toxins on this slide
Do we need to know them all?
