The Na,K-ATPase is a ubiquitous plasma membrane enzyme which is responsible for the establishment of Na+ and K+ homeostasis in animal cells. In the small intestine, the establishment of an electrochemical Na+ gradient at the apical membrane of the villus absorptive cell is crucial for net nutrient and electrolyte absorption. Na,K-ATPase is made up of a large (112KDa) catalytic $ alpha$ subunit, and a glycosylated (35KDa) $ beta$ subunit. Thus far, 3 isoforms for both the $ alpha$ and $ beta$ subunit have been described. We sought to characterize both age-related changes and regional changes in levels of small intestinal Na-K ATPase activity and subunit isoform expression (except $ beta$3) during the postnatal development of the rat. In the proximal small intestine, the specific activity of Na,K-ATPase measured in subcellular fractions gradually rose, while in the distal segment, this rise was less marked. A proximal to distal gradient in Na,K-ATPase activity was demonstrated in post-weaned rats. Only $ alpha$1 and $ beta$1 subunit isoforms were detectable by Western blotting and their expression paralleled the age-specific and regional changes observed in the levels of Na,K-ATPase activity. In addition, the glycoprotein $ beta$1 demonstrated an increase in molecular weight during ontogenesis. The results of this study show important changes in the activity and subunit isoform expression of the Na,K-ATPase during postnatal development of the rat.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.26130 |
| Date | January 1993 |
| Creators | Sauriol, Nathalie |
| Contributors | Wild, Gary E. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Anatomy.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001397200, proquestno: MM94517, Theses scanned by UMI/ProQuest. |
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