Transport and storage of 5-hydroxytryptamine in pancreatic β-cells
Forskningsoutput: Tidskriftsbidrag › Artikel i vetenskaplig tidskrift
To elucidate the role of biogenic amines in insulin secretion, pancreatic islets rich in β-cells were microdissected from obese-hyperglycemic mice and were incubated with 14C-labelled 5-hydroxytryptamine (5-HT). The saturability of uptake and the fact that 5-HT was accumulated to high levels indicated that the β-cells possess a transport system with great capacity for this amine. The initial uptake was not sensitive to glucose or diazoxide. Efflux of radioactivity from islets preloaded with 14C-labelled 5-HT exhibited complex kinetics suggesting incorporation of the amine into some less mobile compartment of the β-cells. This compartment may be the insulin-containing secretory granules, since homogenization and centrifugation of preloaded islets revealed closely parallel sedimentation profiles for insulin and 14C. The apparent co-sedimentation of insulin and 5-HT probably reflects the ultrastructural organization of the β-cells, as insignificant radioactivities were recovered in the sediments after adding 14C-labelled 5-HT to homogenized islets. Furthermore, gel filtration of insulin on 5-HT-equilibrated Sephadex G-50 did not indicate any great affinity of insulin for the amine. Neither glucose nor glibenclamide could be shown to mobilize granule-bound 5-HT from intact β-cells. In these experiments insulin release was slow despite a glucose concentration as high as 20 mM. It seems possible that co-storage of insulin and 5-HT reduces the ability of β-granules to undergo normal emiocytosis.
Ämnesklassifikation (UKÄ) – OBLIGATORISK
|Status||Published - 1972 mar 1|
|Peer review utförd||Ja|