Exogenous surface-active phospholipid protects Necturus gastric mucosa against luminal acid and barrier-breaking agents.
The nature of the protective action of exogenous surface-active phospholipid on gastric mucosa was studied in isolated Necturus antral mucosa by measuring intracellular pH and intraepithelial potentials and resistances with a microelectrode technique. Exposure of the antral mucosa to luminal pH 2 acidified intracellular pH in surface epithelial cells by 0.6-0.3 pH units. A 20-minute pretreatment with exogenous (pulmonary) surfactanlike phospholipid completely abolished this effect. Obviously, phospholipid protected the mucosa against intracellular acidosis by decreasing the apical cell membrane conductance to H+ (and other ions), because it increased apical cell membrane resistance by +108% and total transcellular resistance by +86% but had no significant effects on paracellular or total transepithelial resistances. In mucosas exposed to three barrier-breaking agents, 10 mmol/L acetylsalicylic acid, 20% (vol/vol) ethanol, and 10 mmol/L taurocholate, at acid luminal perfusate (pH 2.0-2.5), a profound intracellular acidification of 0.9-1.3 pH units/15 min occurred. Pretreatment of the tissue with phospholipid significantly opposed intracellular acidification, but the modulatory influences on the changes in intraepithelial potentials or resistances were less conspicuous and mostly insignificant.
Kiviluoto
T
T
II Department of Surgery, Helsinki University Central Hospital, Finland.
Paimela
H
H
Mustonen
H
H
Kivilaakso
E
E
D000818:Animals; D001241:Aspirin / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology; D005744:Gastric Acid; D005753:Gastric Mucosa / Q000187:drug effects* / Q000502:physiology; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009338:Necturus maculosus; D010743:Phospholipids / Q000494:pharmacology*; D013501:Surface-Active Agents / Q000494:pharmacology*; D013656:Taurocholic Acid / Q000494:pharmacology
D010743:Phospholipids; D013501:Surface-Active Agents; D000431:Ethanol; D013656:Taurocholic Acid; D001241:Aspirin