where is your rectal gland? karen hong warren pan chela brown ashish sharma brittany scarpato
TRANSCRIPT
Where is your rectal gland?
Karen Hong Warren Pan Chela Brown Ashish Sharma Brittany Scarpato
Dogfish Shark (Squalus acanthias) rectal gland:a great model
• Purpose of the rectal gland• A single cell type--highly specialized for
transepithelial salt secretion• Holds the World Record for: Na/K ATPase activity,
Na/K/2Cl cotransporter activity (50x greater than mammalian kidney), and CFTR chloride channel activity
• One artery (usually), vein, duct--easy to cannulate and use for perfusion studies
• Model for hormonal regulation
K+Na+
BL SideApical Side
Na+
K+
2 Cl-
CFTRCl-
K+
-70mV
TAL vs the shark rectal glandAbsorption v. Secretion
K+Na+
BL SideApical Side
K+
Na+
K+
2 Cl-
Cl-
Barttin
ClC-Kb
Rectal Gland Cell Model
K+Na+
Basolateral SideApical Side
Na+
K+
2 Cl-
CFTRCl-
K+
cAMP
5’AMPC
ATP
PDE
K+
Rectal Gland Cell Model
K+Na+
Basolateral SideApical Side
Na+
K+
2 Cl-
CFTRCl-
K+ BaCl2 +
cAMP
5’AMPC
ATP
PDE
IBMX
Forskolin
K+
Bumetanide
Ouabain
Rectal Gland Cell Model
K+Na+
Basolateral SideApical Side
Na+
K+
2 Cl-
CFTRCl-
K+
K+
K+
K+
K+
K+
Cl-
Cl-
Cl-
-70mv
-15mv
Rectal Gland Cell Model
K+Na+
Basolateral SideApical Side
Na+
K+
2 Cl-
CFTRCl-
K+
K+
K+
K+
K+
K+
Cl-
Cl-
Cl-
Approaching -15mv
-15mv K+
K+
K+
K+K+
BaCl2 +
K+
K+
K+
K+
K+
K+
The Shark Rectal Gland: A Model Secretory Epithelium
Hypothesis: Does inhibition of basolateral membrane proteins inhibit chloride secretion through apical CFTR?
In Vivo Dissection In Vitro Perfusion
Methods
Artery
Duct
Vein
Set-up
0 10 20 30 40 50 60 70 80 90 1000
500
1000
1500
2000
2500
R3
Time (min)
Ch
lori
de
Se
cre
tio
n (
µE
q/h
/g)
BasalF + I Bumet
F + IF + I Ouabain
F + IF + I
0 10 20 30 40 50 60 70 80 90 1000
500
1000
1500
2000
2500
R4
Time (min)
Ch
lori
de
Se
cre
tio
n (
µE
q/h
/g)
F + I F + IBasal F + IBaCl2F + I
Ouabain + BaCl2F + I
Conclusions
• Bumetanide inhibits cotransporter• Ouabain inhibits the ATPase enzyme, which in
turn inhibits the cotransporter• Barium chloride inhibits by depolarization
Future Suggested Experiments
• Administer bumetanide and barium chloride• All three drugs• Change the order the drugs are administered • Vary the perfusion times for each drug• Change the basal solution composition• Increase extracellular potassium
