A genetic polymorphism of sheep red cells characterized by differences in the intracellular K$ sp+$ concentration of their mature red cells reflects differences in their Na/K pump activity as well as pump kinetics. This polymorphism is linked to the ML blood group system, as follows. Homozygous high-K$ sp+$ (HK) cells possess only M antigen, whereas homozygous low-K$ sp+$ (LK) cells have an antigen, L$ rm sb{p},$ which is an endogenous inhibitor of the Na/K pump since isoimmune antiserum, anti-L$ rm sb{p},$ stimulates the Na/K pump of LK cells by relieving this inhibition. In this study, it is shown that the $ rm L sb{p}$ antigen is a molecular entity distinct from the pump. Thus, anti-$ rm L sb{p}$ stimulated the activity (ouabain-sensitive $ rm sp{86}Rb sp+(K sp+)$ influx) of exogenous rat kidney pumps incorporated by fusion of kidney microsomes into immature LK red cells. Moreover, the $ rm L sb{p}$ antigen is responsible for the changes in pump kinetics associated with maturation of LK sheep red cells. The evidence is that treatment of immature LK cells with either anti-L$ rm sb{p}$ or trypsin (which cleaves the $ rm L sb{p}$ antigen) prevents the maturation-associated change in kinetics of the pumps, normally from one of no inhibition (immature cells) to that of marked inhibition by intracellular K$ sp+$ (mature cells). In addition, it was shown that kidney pumps delivered into immature LK red cells develop sensitivity to inhibition by intracellular K$ sp+$ following maturation of the cells in vitro. Mature LK cells have fewer pumps than mature HK cells and, therefore, another question addressed was whether the $ rm L sb{p}$ antigen promotes the greater loss of pumps in LK red cells during maturation. It was observed that modification of the $ rm L sb{p}$ antigen of immature LK cells with either anti-L$ rm sb{p}$ or trypsin diminished the subsequent loss of pumps during maturation in vitro. It was shown also that there is little decline in the number of $ rm
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.41790 |
| Date | January 1994 |
| Creators | Xu, Zheng-Chun |
| Contributors | Blostein, Rhoda (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 | Doctor of Philosophy (Division of Experimental Medicine.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001397876, proquestno: NN94724, Theses scanned by UMI/ProQuest. |
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