Neurophys Flashcards
2 factors contributing to RMP
Na/K ATPase, leak channels
important inward rectifying K channel type
Katp
What is K+ leak (inward rectifying) made of
tetramer, 2 transmembrane segments and p loop for ion selectivity
What are Katp made of
channel-forming subunits and 4 large regulatory subunits (sulfonylurea receptors)
How does ATP affect Katp
if ATP levels low, Katp activate and cause K+ efflux –> hyperpolarization –> reduction in energy consumed from ion pumps to restore membrane voltage after AP
How do sulfonylureas work
Used to treat diabetes mellitus, inhibit Katp channels –> depolarization –> insulin secretion
K channels that are effectors for GPCRs
GIRK, cause membrane hyperpolarization upon activation, activated by B-gamma subunit
what allows for Na+ selectivity
lysine, alanine, glutamate, aspartate ring (glutamate and aspartate in Ca+2)
what amino acids are the basis for voltage-sensing
S4 helix arginine, lysine (+ charged)
what activates K+ and Na+ channels
rotation of lower end of S6 segment
What causes K+ channel inactivation
amino terminal domain blocks pore (ball and chain)
heart VGK channel
hERG, responsible for Ikr, blocking prolongs effective refractory period (relative), reentry
Brain VGK channel
M-current is effective for epilepsy tx
