title: Anion effects on fluid absorption from rat jejunum perfused in vivo.
abstract: Perfusion of rat jejunal segments in vivo with an isotonic, HCO3-free SO4-Ringer solution resulted in low rates of net sodium (JNanet) and water absorption. When the perfusion fluid was changed to one containing 25 mM Na2SO3, JNanet increased from 4.7 +/- 1.2 to 11.6 +/- 1.5 (SE) mumol X cm-1 X h-1 (P less than 0.001). This increased absorption was accompanied by comparable increases in chloride and water absorption, occurred without a detectable change in potential difference across the perfused segment, and was readily reversed on reinstitution of perfusion with SO4-Ringer. Perfusion with SO3-Ringer had no effect on electrolyte absorption from terminal segments of rat ileum. Addition of L-phenylalanine stimulated absorption from SO4-Ringer perfusate but not from SO3-Ringer perfusate. Addition of 25 mM NaHCO3 to SO4-Ringer perfusate caused parallel increases in JNanet and JHCO3net; when 25 mM NaHCO3 was added to SO4-Ringer perfusate that also contained 25 mM NaSCN, the same increase in JHCO3net occurred but was not associated with any increase in JNanet. These results indicate a potent effect of SO2-3 and HCO-3 to stimulate JNanet from rat jejunum but not from ileum. These anion effects on intestinal transport in vivo resemble their effects on ATPase activity of brush-border fractions from small intestine in vitro and raise the possibility that these effects on ion transport could be mediated through the changes in brush-border ATPase activity, which are brought about by exposure to these anions, although other explanations are also possible.
mesh_terms: D000818:Animals; D000838:Anions; D001639:Bicarbonates / Q000378:metabolism / Q000494:pharmacology*; D002712:Chlorides / Q000378:metabolism; D005260:Female; D007408:Intestinal Absorption / Q000187:drug effects*; D007583:Jejunum / Q000378:metabolism*; D008297:Male; D010477:Perfusion; D010649:Phenylalanine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism; D017693:Sodium Bicarbonate; D013431:Sulfates / Q000494:pharmacology; D013447:Sulfites / Q000494:pharmacology*; D014867:Water / Q000378:metabolism
chemical_list: D000838:Anions; D001639:Bicarbonates; D002712:Chlorides; D013431:Sulfates; D013447:Sulfites; D014867:Water; C012036:sodium sulfate; D010649:Phenylalanine; D017693:Sodium Bicarbonate; D012964:Sodium; C025026:sodium sulfite