Maturation and aging-associated changes in membrane transport of sheep reticulocytes of the high-K('+) and low-K('+) genotypes were studied. The results indicate that during short term (less than 10 days) in vitro maturation, there is a progressive decrease in ouabain-sensitive Na('+),-K('+)-pump activity (('86)Rb('+) uptake in low-K('+) cells) and Na('+)-ATPase activity (high-K('+) cells). However, during long term (several weeks) in vivo maturation in which HbC was used as a marker of newly formed reticulocytes, kinetic changes, as well as a decline in total activity, were observed. / The effect of metabolic depletion on the maturation-associated loss of two membrane transport functions was also studied using in vitro incubation. Both Na('+)-dependent glycine transport and the Na('+),K('+)-pump, estimated from measurements of the number of ('3)H-ouabain binding sites per cell, were decreased during maturation. ATP also enhanced the decrease in both activities when a 'reconstituted' vesicle system comprised of inside-out vesicles plus cell lysates was incubated at 37(DEGREES)C. Associated with this ATP-dependent loss of activity was an increase in the amount of concomitantly measured ninhydrin-positive material. It is concluded that the loss of certain functions during reticulocyte maturation is retarded by metabolic depletion. / Membrane vesicles of distinct sidedness were prepared from sheep reticulocytes. Using these vesicles the Na('+)-dependent glycine transport system was found to be symmetrical with respect to: (a) the Na('+) dependency of glycine transport, (b) the ability to accumulate glycine against a concentration gradient, (c) the Na('+): glycine stoichiometry, i.e. two Na('+) ions are transported per molecule of glycine, and (d) the apparent Michaelis-Menten constants for Na('+) and glycine.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.71866 |
| Date | January 1984 |
| Creators | Weigensberg, Andrew Mark. |
| 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 | Doctor of Philosophy (Department of Biochemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000218658, proquestno: AAINK66588, Theses scanned by UMI/ProQuest. |
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