GI Absorption of Salt and Water

Question 1

Mechanism and action of VIP

Answer 1

VIP binds to Adenylate Cylase to increase cAMP levels
cAMP binds to CFTR and increases opening time for this Cl-, HCO3- channel.
This leads to greater secretion

Question 2

Mechanism and action of vibrio cholerae

Answer 2

VIP activates cAMP
leads to permanent activation of cAMP leading to opening of CFTR channels
results in huge loss of water

Question 3

Mechanism and action of E. choli

Answer 3

E. Choli produces heat stable toxin (HST) that has structure similar to guanylin
HST activates cGMP leading to opening of CFTR
a.k.a travers diarrhea