Epithelial Chloride Channels 2

Question 1

CF information

Answer 1

1 in 2500 caucasian births
dysfunctional wet epithelium
block pancreatic ductules
inability to clear mucus

Question 2

diagnosing CF

Answer 2

CF sweat 3-5 times more NaCl

Question 3

sweat duct normal

Answer 3

NaCl in sweat gland and reabsorbed higher up

water onto skin surface

Question 4

Paul Quinton 1983 - name of paper

Answer 4

chloride impermeability in CF

Question 5

Paul Quinton 1983 findings

Answer 5

potential difference across CF sweat duct epithelial higher than normal
PNa/PCl 10 fold higher
reduced Cl permeability accounts for CF symptoms

Question 6

non cf vs cf sweat duct epithelium

Answer 6

apical –> basolateral membrane
absorption of chloride and sodium
excrete chloride, Na via Na/K ATPase
apical Cl disturbed, not reabsorbed

Question 7

Michael J Welsh 1986

Answer 7

Apical membrane Chloride channel in human tracheal epithelium

Question 8

What did Michael J Welsh do in 1986?

Answer 8

patch clamp study of apical Cl channels in tracheal epithelium
ORCC

Question 9

outward and inwards current movement of ions

Answer 9

outward = move in
inward = move out
direction +ve charge moves

Question 10

Who first identified ORCCS?

Answer 10

MIchael J Welsh

Question 11

What is a symmetrical channel?

Answer 11

ions move in both directions

I/V proportional

Question 12

epithelial chloride channels - ORCCS

Answer 12

more current at positive voltages than at negative
positive inside - outward current
positive voltages and more current
let more chloride from outside to inside
airway - trying to find channel let chloride out of cell

Question 13

Frizzell 1986 - other paper which came out similar?

Answer 13

Altered regulation of airway epithelial cell chloride channel in CF
Chloride and potassium channels in CF airway

Question 14

Frizzel and Welsh 1986 findings

Answer 14

failure of beta adrenergic agonists to activate ORCCs in CF airway

Question 15

1987 Schoumacher

Answer 15

phosphorylation fails to activate chloride channels in CF airway

Question 16

Schoumacher 1987 findings

Answer 16

failure of PKA to activate ORCCS in CF airway epithlial cells
ORCCS were present in CF and activated by strong depolarisation

Question 17

1988 Li

Answer 17

cAMP dependent PKA open Cl channels in normal but not CF airway epithelium

Question 18

LI 1989

Answer 18

Regulation of chloride channels by PKC in normal and CF epithelium

Question 19

findings from Li 1989

Answer 19

failure of PKA activate ORCCS in CF - defect of channel or regulatory protein
PKC activated ORCCS in normal but not CF
defective transduction from phosphorylation sites to channel gating mechanism

Question 20

1989 Gray

Answer 20

2 types of Cl channel on duct cells from human fetal pancreas

Question 21

who found SLCC?

Answer 21

gray et al in 1989

Question 22

2 types of chloride channels

Answer 22

SLCC in apical membrane of pancreatic duct cells

ORCCS infrequently

Question 23

what activated SLCC?

Answer 23

secretin and cAMP

Question 24

conductance of SLCC

Answer 24

small and linear