Other channels

Question 1

What are hERG channels

Answer 1

human ether a-go-go related gene
alpha subunit of Kv1.1
the rare mutation and drugs can cause long QT syndrome

Question 2

What is QT syndrome and what can it cause

Answer 2

extended duration in ventricular action potentials

causing arrhythmias because decreased repol of heart ap, therefore the inward current can trigger early depol

Question 3

list the hERG drug interactions

Answer 3

anti psychotics, some antibiotics and antiarrhythmic drugs

Question 4

describe hERG regular function

Answer 4

its a voltage gated channels that is activated by depol
it has slow activation and deactivation bc the probability of moving s$ is low
it has rapid recovery from inactivation so it doesnt interfere with ca2+ plateau

Question 5

What do TRP channels do in flies

Answer 5

mediate light perception = PLC -> IP3 + CA -> channel opening

Question 6

why are TRP channels called transient receptor potential channels

Answer 6

because a mutation in TRP causes a transient response

Question 7

describe the structure of TRP channels and how they are activated

Answer 7

tetrameric with 6 transmembrane domains per subunit
act with depol at Ca entry
linked to PLC
temperature and ligands are activators

Question 8

what are the functional roles of TRPs

Answer 8

somatosensation = mechano, propriom thermo

TRPV1, TRPM8, TRPA1 = noci

Question 9

describe TRPV1

Answer 9

venoms modulate receptor channels function
shock, paralysis, death
acute pain, neurogenic inflammation
irreverisble agonists

Question 10

Describe TRPM8

Answer 10

activated by menthol + cold stimuli
deficiency = no preference for hot or cold
antagonists could become analgesics

Question 11

Describe TRPA1

Answer 11

detects chemical irritants and inflammatory + pungent agents

Question 12

Describe the therapeutic potential of TRPs

Answer 12

block sensitising actions of inflam agents without altering heat sensitivity
TRP channels are needed for the detection of noxious substances and are implicated in cancer development, asthma, cardiac hypertrophy

Question 13

Describe the CFTR cl channel

Answer 13

decrease in cl and bicarbonate secretion from submucosal glands because of viscous acidic surface liquid
promotes bacterial colonisation

Question 14

describe mutation of CLC-1 CL- channel

Answer 14

myotonia = inherited CL- chan mutation

conductance in skeletal muscle = exaggerated contraction and increase in muscle excitability

Question 15

Describe CaCls

Answer 15

activated slowly by depol ca entry
control fertilisation, olfaction, epithelium secretion, smooth muscle contraction
regulated by CA and CA modulated kinases

Question 16

What are gap junctions and their main functions

Answer 16

electrical synapses to allow bidrectional flow
can be gated and show recitification in current flow
they pull together neurons for uniform spread of smooth, wave-like depol
present in early development, glial + muscle cells
6 subunits per channel

Question 17

how are gap junctions involved in early development

Answer 17

interconnectivity between immature neurons shown by dye coupling
development of uncoupling overlaps with the formation of chemical synapses

Question 18

how are gap junctions involved in CNS injury

Answer 18

send pro-survival signals or pathological death signals through glial cells

Question 19

describe the features of inward rectifiers

Answer 19

act downstream of GPCRs
nicotinic + muscarinic
M1 M2 M3 couple with Gq to activate PLC

Question 20

what does signal cascade of PLC do

Answer 20

alters Kir activation

Question 21

Describe the structure of inward rectifiers

Answer 21

2 transmembrane domains with tetramic channels
equivalent to 5th and 6th transmembrane domain and intervening KV pore loop
lack S4

Question 22

how are Kirs related to EPSPs and IPSPs

Answer 22

GPCR -> EPSPS by decreases Kir to increase excitability

GPCR -> IPSPs by increasing Kir to decrease excitability