| Title: | Na(+)-dependent intestinal glucose absorption mechanisms and its luminal Na(+) homeostasis across metamorphosis from tadpoles to frogs |
| Author(s): | Ishizuka N; Nagahashi M; Mochida Y; Hempstock W; Nagata N; Hayashi H; |
| Address: | "Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka, Japan" |
| Journal Title: | Am J Physiol Regul Integr Comp Physiol |
| DOI: | 10.1152/ajpregu.00249.2021 |
| ISSN/ISBN: | 1522-1490 (Electronic) 0363-6119 (Linking) |
| Abstract: | "The abrupt morphological changes of the intestine during metamorphosis have been detailed in frogs. The features of intestinal metamorphosis are shortening of the intestine and remodeling of the intestinal epithelium. It is believed that the purpose of the morphological changes of the intestine is adaptation from aquatic herbivorous to carnivorous life. However, little is known about the physiological importance of these morphological changes. To elucidate the functional changes during metamorphosis, we measured luminal Na(+) concentrations and Na(+)-dependent glucose uptake in tadpoles and adult African clawed frogs Xenopus laevis. The small intestine was isolated and divided into four segments in length, the luminal contents collected for analysis of ion concentration by ion chromatography. Phlorizin-sensitive glucose-induced short-circuit current (DeltaI(sc)) was measured in intestinal preparations mounted in Ussing chambers. Although dietary sodium intake was extremely low in tadpoles, luminal Na(+) concentration gradually increased along the proximal to the middle part of the intestine (>70 mM), and this Na(+) concentration was comparable with that of carnivorous adult frogs. The increment of glucose-induced DeltaI(sc) was observed in tadpole intestine. We also measured the DeltaI(sc) induced by acetic acid, which is the major short-chain fatty acid produced by fermentation. The expression levels of mRNA for Na(+)-dependent glucose transporter 1 and tight junction protein claudin-15 in each intestinal segment was measured. These results suggest that luminal Na(+) homeostasis is important and luminal Na(+) is kept at a high concentration for Na(+)-dependent nutrient absorption mechanisms" |
| Keywords: | "Animals *Glucose/metabolism Larva *Intestine, Small Intestines Intestinal Mucosa/metabolism Intestinal Absorption Homeostasis Na+-dependent nutrient uptake Xenopus laevis leaky epithelia luminal Na+ concentration tight junction;" |
| Notes: | "MedlineIshizuka, Noriko Nagahashi, Mina Mochida, Yuina Hempstock, Wendy Nagata, Nozomi Hayashi, Hisayoshi eng Research Support, Non-U.S. Gov't 2023/03/21 Am J Physiol Regul Integr Comp Physiol. 2023 May 1; 324(5):R645-R655. doi: 10.1152/ajpregu.00249.2021. Epub 2023 Mar 20" |
