title: Relations of weak-electrolyte transport and acid-base metabolism in rat small intestine in vitro.
abstract: The jejunal and ileal regions of rat small intestine in vitro exhibit different patterns of weak-electrolyte transport and acid-base metabolism. The jejunal pattern of weak-electrolyte transport is net transport of weak acids M yields S and of weak bases S yields M (M, mucosal; S, serosal), and the pattern of acid-base metabolism is luminal acidification and serosal alkalinization. In the absence of sodium or in the presence of metabolic inhibitors, weak-electrolyte transport and serosal alkalinization are inhibited, but luminal acidification is not inhibited. The ileal pattern of weak-electrolyte transport is the opposite of that of the jejunum and may be associated with the presence of a luminal alkalinization process observed in this region. In the absence of chloride the ileal patterns of weak-electrolyte transport and acid-base metabolism become similar to those of the jejunum. It is suggested that these observations support a previously proposed model for weak-electrolyte transport in the intestine consisting of a series three-compartment system in which the pH of the intermediate compartment is greater than that of the bulk phases.
mesh_terms: D000081:Acetamides / Q000494:pharmacology; D000136:Acid-Base Equilibrium; D000588:Amines / Q000494:pharmacology; D000963:Antimetabolites / Q000494:pharmacology; D001565:Benzoates / Q000378:metabolism; D001593:Benzyl Compounds / Q000494:pharmacology; D001639:Bicarbonates / Q000378:metabolism; D001692:Biological Transport; D002712:Chlorides / Q000378:metabolism; D002794:Choline / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D005463:Fluoroacetates / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007082:Ileum / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D007421:Intestine, Small / Q000378:metabolism*; D007461:Iodoacetates / Q000494:pharmacology; D007583:Jejunum / Q000378:metabolism; D008954:Models, Biological; D012704:Serous Membrane / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013431:Sulfates / Q000494:pharmacology
chemical_list: D000081:Acetamides; D000588:Amines; D000963:Antimetabolites; D001565:Benzoates; D001593:Benzyl Compounds; D001639:Bicarbonates; D002712:Chlorides; D004140:Dinitrophenols; D005463:Fluoroacetates; D007461:Iodoacetates; D013431:Sulfates; D012964:Sodium; D002794:Choline