title: Lack of functionally active sweet taste receptors in the jejunum in vivo in the rat.
abstract: BACKGROUND
  When studied in enterocyte-like cell lines (Caco-2 and RIE cells), agonists and antagonists of the sweet taste receptor (STR) augment and decrease glucose uptake, respectively. We hypothesize that exposure to STR agonists and antagonists in vivo will augment glucose absorption in the rat.
  
  
  METHODS
  About 30-cm segments of jejunum in anesthetized rats were perfused with iso-osmolar solutions containing 10, 35, and 100 mM glucose solutions (n = 6 rats, each group) with and without the STR agonist 2 mM acesulfame potassium and the STR inhibitor 10 μM U-73122 (inhibitor of the phospholipase C pathway). Carrier-mediated absorption of glucose was calculated by using stereospecific and nonstereospecific (14)C-d-glucose and (3)H-l-glucose, respectively.
  
  
  RESULTS
  Addition of the STR agonist acesulfame potassium to the 10, 35, and 100 mM glucose solutions had no substantive effects on glucose absorption from 2.1 ± 0.2 to 2.0 ± 0.3, 5.8 ± 0.2 to 4.8 ± 0.2, and 15.5 ± 2.3 to 15.7 ± 2.7 μmoL/min/30-cm intestinal segment (P > 0.05), respectively. Addition of the STR inhibitor (U-73122) also had no effect on absorption in the 10, 35, and 100 mM solutions from 2.3 ± 0.1 to 2.1 ± 0.2, 7.7 ± 0.5 to 7.2 ± 0.5, and 15.7 ± 0.9 to 15.2 ± 1.1 μmoL/min/30-cm intestinal segment, respectively.
  
  
  CONCLUSIONS
  Provision of glucose directly into rat jejunum does not augment glucose absorption via STR-mediated mechanisms within the jejunum in the rat. Our experiments show either no major role of STRs in mediating postprandial augmentation of glucose absorption or that proximal gastrointestinal tract stimulation of STR or other luminal factors may be required for absorption of glucose to be augmented by STR.
authors.affiliation: Department of Surgery and Gastroenterology Research Unit, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: Rizwan M
authors.initials: RM
authors.lastname: Chaudhry
authors.forename: Alok
authors.initials: A
authors.lastname: Garg
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Abdelfatah
authors.forename: Judith A
authors.initials: JA
authors.lastname: Duenes
authors.forename: Michael G
authors.initials: MG
authors.lastname: Sarr
mesh_terms: D000818:Animals; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000502:physiology*; D020895:Enterocytes / Q000166:cytology* / Q000378:metabolism; D004963:Estrenes / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D051273:Glucose Transporter Type 2 / Q000502:physiology; D007408:Intestinal Absorption / Q000187:drug effects / Q000502:physiology*; D007583:Jejunum / Q000166:cytology / Q000378:metabolism*; D008297:Male; D023421:Models, Animal; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D011917:Rats, Inbred Lew; D013843:Thiazines / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
chemical_list: D004963:Estrenes; D051273:Glucose Transporter Type 2; D011760:Pyrrolidinones; C495683:Slc2a2 protein, rat; D013843:Thiazines; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D010738:Type C Phospholipases; D005947:Glucose; C006362:acetosulfame
keywords: Acesulfame potassium; Apical translocation; GLUT2; Glucose absorption; SGLT1; Sweet taste receptors; U73122