title: Demonstration and modification of intervillous pH profiles in rat small intestine in vitro.
abstract: The intervillous pH profiles along the crypt villus axis in different regions of the rat small intestine were measured in vitro by using pH-sensitive liquid ion-exchanger microelectrodes. A characteristic pH profile was observed in the duodenum and jejunum. A region of low pH was detected in the upper parts of the villi (pH 6.65 +/- 0.06 to 6.85 +/- 0.07), whereas pH at the villus base was always higher. In the ileum no gradient was observed (pH 7.26 +/- 0.05 to 7.31 +/- 0.05). Preincubation of the tissue in situ with 10 mM theophylline for 1 h caused an increase in the villus base pH in the jejunum (pH 7.24 +/- 0.04) and ileum (7.44 +/- 0.04) followed by a subsequent increase of the pH in the upper part of the villi. These results indicate that the low pH in the upper intervillous space may be related to H+ secretion occurring from the mature enterocytes, whereas the crypt cells may secrete a rather neutral or slightly alkaline fluid. Alkaline secretion from the crypts may be increased by theophylline, which changes the levels of cyclic nucleotides in the mucosa.
authors.affiliation: Institute of Nutrition, Justus-Liebig-University, Giessen, Federal Republic of Germany.
authors.forename: H
authors.initials: H
authors.lastname: Daniel
authors.forename: C
authors.initials: C
authors.lastname: Fett
authors.forename: A
authors.initials: A
authors.lastname: Kratz
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D004386:Duodenum / Q000502:physiology; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods; D006863:Hydrogen-Ion Concentration; D007082:Ileum / Q000502:physiology; D066298:In Vitro Techniques; D007421:Intestine, Small / Q000187:drug effects / Q000502:physiology*; D007583:Jejunum / Q000502:physiology; D008297:Male; D008839:Microelectrodes; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013806:Theophylline / Q000494:pharmacology
chemical_list: D013806:Theophylline; D000242:Cyclic AMP