carotid body 2

Question 1

hypoxia: can also measure nerve fiber?

Answer 1

measure individual afferent sinus nerve fiber: during hypoxia, you see an increase in action potential frequency (same thing you’d see in a single glomus cell)

Question 2

similar pO2 dependence of what three things?

Answer 2

CSN activity, calcium signal, and transmitter release from glomus cells: high/normoxia = low % of maximum, while decrease in pO2 is an exponential increase

Question 3

oxygen sensing in glomus cells in volves ____ of __ channels

Answer 3

inhibition of K+ channels

Question 4

glomus cells: K+ channel open/close significance?

Answer 4

K+ channels open = K+ leaves cell, so hyperpolarization. closing these channels would mean depolarization (so during hypoxia these K+ channels are closed)

Question 5

glomus cells: after closing K+ channels what happens

Answer 5

depolarization = activate voltage gated calcium channels = increase in calcium = neurotransmitter release and exocytosis to activate sensory nerve of carotid sinus nerve

Question 6

rabbit glomus cell experiment: hypoxia’s effect on K+ current?

Answer 6

hypoxia reduces the amplitude of the outward K+ current evoked by depolarization. no change in inward current, outward current looks smaller = you’re suppressing the outward potassium current

Question 7

outward/inward negative or positive?

Answer 7

outward current = positive charge out. inward current = positive charge in.

Question 8

hypoxia sensitive K+ channel belongs to what family

Answer 8

Kv4: delayed rectified current

Question 9

BKCa channels: are what? what happens if you block it?

Answer 9

large conductance calcium activated K+ channels. block = depolarization. (hypoxia = reduces amplitude of voltage and calcium dependent K+ current.

Question 10

BKCa channel inhibitor? effects?

Answer 10

charybdotoxin ChTX = depolarization - mimics hypoxia

Question 11

TASK channels: what

Answer 11

K+ leak channels

Question 12

hypoxia effect on TASK channels

Answer 12

hypoxia: reduces amplitude of voltage independent TASK current

Question 13

TASK channels responsible for

Answer 13

setting membrane potential of rat glomus cells

Question 14

what organelle in glomus cells sensitive to hypoxia

Answer 14

mitochondria: very sensitive changes in depolarization levels depending on oxygen levels (which you don’t see in a superior ganglion neuron)

Question 15

mitochondria and depolarization and hypoxia?

Answer 15

hypoxia = suppresses mitochondria activity (but increase in AP discharge) = reduction in ATP = activation of AMPK

Question 16

compound C

Answer 16

inhibits AMPK = reduces hypoxia mediated CSN discharge

Question 17

AICAR

Answer 17

activates AMPK: stimulates CSN discharge

Question 18

actions of NTs on CSN: what is excitatory and inhibitory

Answer 18

exciatory: ACh on nAChR, but mostly ATP on P2X channels. inhibitor = DA on D2 receptors