Role of polarization of gastric EMFs in evaluation of contemporary HCl models.
The neutral proton pump (NP) model postulates a neutral exchange of K+ for H+ across the secretory membrane and the electrogenic proton pump (EP) model an electrogenic proton pump. Previous evidence is briefly reviewed and polarization of EMFs by transmucosal voltage clamping (VC) is presented. During VC, open circuit potential difference (PD) (VOC) is obtained by breaking the circuit for 2 s (after dielectric capacitors have discharged). The magnitude of polarization in Cl- media is less than in Cl(-)-free media, presumably due to the high conductance of Cl- paths. The magnitude in Cl(-)-free media is from 35 to 50 mV for a VC of 100 mV (nutrient side positive). The Na+/K(+)-ATPase is not essential because with choline sulphate media polarization is typical. With Cl(-)-free media, VOC versus IH (H+ rate) is exponential but (VC-VOC) versus IH is linear. Polarization on the basis of the NP model would be due to changes in K+ diffusion potentials. However, with 80 mM K+ on both sides (Cl(-)-free media) polarization is typical. We conclude that polarization cannot be due to a change in K+ diffusion potentials but to polarization of the EP model. The problem remains of how to incorporate the important finding of the H+/K(+)-ATPase into a model for the intact tissue.
Rehm
W S
WS
University of Louisville, Kentucky.
Carrasquer
G
G
Schwartz
M
M
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology; D002712:Chlorides / Q000378:metabolism; D004553:Electric Conductivity; D005744:Gastric Acid / Q000378:metabolism*; D005753:Gastric Mucosa / Q000378:metabolism / Q000502:physiology*; D017506:H(+)-K(+)-Exchanging ATPase; D008564:Membrane Potentials / Q000502:physiology; D008954:Models, Biological
D002712:Chlorides; D000251:Adenosine Triphosphatases; D017506:H(+)-K(+)-Exchanging ATPase