Human spasmolytic polypeptide decreases proton permeation through gastric mucus in vivo and in vitro.
Exogenously administered trefoil peptides are gastroprotective in rat injury models. We hypothesized that trefoil-associated gastroprotection occurred by decreasing the rate of proton permeation through mucus. Gastric surface cell intracellular pH and mucus gel thickness were measured by in vivo microscopy. Gastric mucosal blood flow was measured by laser-Doppler flowmetry. The effect of human spasmolytic peptide (hSP) on H+ diffusion through 5% purified porcine mucin was measured using an Ussing chamber. Buffering action of mucin was measured by titration. In vivo, gastric mucosal blood flow and mucus gel thickness were not affected by any of the treatments. Topical hSP, but not intravenous hSP, decreased initial acidification rate and elevated the intracellular pH of gastric surface cells during luminal acid challenge. In in vitro studies, hSP dose dependently decreased the diffusion coefficient of H+ through 5% porcine mucin solution. hSP had no significant effect on the buffering action of mucin solutions. These data support our hypothesis that hSP interacts with gastric mucin in a manner that inhibits proton permeation through the mucus gel layer.
Tanaka
S
S
Medical Service, West Los Angeles Veterans Affairs Medical Center, California, USA.
Podolsky
D K
DK
Engel
E
E
Guth
P H
PH
Kaunitz
J D
JD
D000818:Animals; D005744:Gastric Acid / Q000378:metabolism*; D005753:Gastric Mucosa / Q000098:blood supply / Q000187:drug effects / Q000502:physiology*; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017078:Laser-Doppler Flowmetry; D008297:Male; D009077:Mucins / Q000187:drug effects / Q000502:physiology; D009124:Muscle Proteins; D009479:Neuropeptides; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects; D013552:Swine; D000071164:Trefoil Factor-2; D000071165:Trefoil Factor-3
D006133:Growth Substances; D009077:Mucins; D009124:Muscle Proteins; D009479:Neuropeptides; D010455:Peptides; C099037:TFF3 protein, rat; C000604008:Tff2 protein, rat; D000071164:Trefoil Factor-2; D000071165:Trefoil Factor-3