Stoichiometry of K+/H+ antiport helps to explain extracellular pH 11 in a model epithelium.
The stoichiometry of K+/H+ antiport was measured fluorometrically by the static head method in highly purified vesicles from goblet cell apical membranes of larval lepidopteran midgut. The measured stoichiometry of 1 K+/2 H+ explains how the antiport results in electrophoretic exchange of extracellular H+ for intracellular K+, driven by the voltage component of the proton-motive force of an H+ translocating V-ATPase that is located in the same membrane. In turn, the exchange of K+ for H+ helps to explain how the midgut contents are alkalinized to a pH of 11.
Azuma
M
M
Zoologisches Institut der Universität, München, Germany.
Harvey
W R
WR
Wieczorek
H
H
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000502:physiology*; D004064:Digestive System; D004848:Epithelium / Q000502:physiology; D005110:Extracellular Space; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007814:Larva; D018402:Manduca; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D028021:Sodium-Potassium-Chloride Symporters
D002352:Carrier Proteins; D028021:Sodium-Potassium-Chloride Symporters; D012964:Sodium; D011188:Potassium