The pathway of receptor-mediated endocytosis in exocrine pancreatic cells of the rat was studied. The pathway was explored using insulin radiolabeled with iodine-125 detectable by the technique of radioautography. / Insulin was seen at the cell membrane soon after administration of the radiolabeled hormone. After 10 and 20 minutes silver grains were found over compartments deep within the cells, at distances greater than 5 half-distances. Grains were also seen to be associated with endosomal vesicles characterized by heavily stained, often fuzzy, membrane. At this time and later times of 45 minutes, grains were observed over zymogen granules. A group of rats was treated with chloroquine to interfere with intracellular vesicle acidification. The results revealed an accumulation of insulin in endosomes and in presecretory and secretory granules. / Degradation of insulin was found to be significantly inhibited by chloroquine in the liver but not in the pancreas. Degradation of insulin in normal rats was found to be slow in the pancreas but fast in the liver. / The results suggest that insulin is internalized to endosomes within which it may be degraded. Internalized insulin was also seen in the trans Golgi network and zymogen granules, especially after chloroquine treatment. This suggests an access route from endocytic to exocytic compartments which may be related to the pathway of sorting of lysosomal proteins. It may also be significant in the transcytosis of insulin to the pancreatic duct.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.74619 |
| Date | January 1990 |
| Creators | Cruz, Javier |
| 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 Anatomy.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001214649, proquestno: AAINN67654, Theses scanned by UMI/ProQuest. |
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