ISSN:
1432-0428
Schlagwort(e):
Amino acid transport
;
insulin
;
somatostatin
;
cholecystokinin octapeptide
;
pancreatic secretion
;
glucose challenge
;
exocrine pancreas (rat)
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Medizin
Notizen:
Summary Regulatory effects of insulin, somatostatin and cholecystokinin on amino acid transport in the isolated perfused rat pancreas have been studied using a rapid dual isotope dilution technique. Uni-directional L-serine transport (15 s) was quantified relative to an extracellular tracer D-mannitol over a wide range of substrate concentrations. In pancreata perfused with 2.5 mmol/l D-glucose, a weighted nonlinear regression analysis of overall transport indicated an apparent Km=14.4±1.6 mmol/l and Vmax=25.9±1.4 μmol ·min−1·g−1 (n=6). Although L-serine transport was stimulated during perfusion with 100 μU/ml bovine insulin, endogenous insulin (7–25 ng·min−1·g−1) released during continuous perfusion with either 8.8 mmol/l or 16.8 mmol/l D-glucose had no such effect. Exogenous somatostatin-14 (250 pg/ml) or cholecystokinin octapeptide (CCK-8, 3 × 10−11mol/l) appeared to increase only the Km for transport. Only CCK-8 evoked a notable protein output (2.9±0.3 mg·30min−1·g−1) and juice flow (68±10μl·30min−1·g −1, n=3) from the exocrine pancreas. When pancreata were perfused with bovine insulin (100 μU/ml) and somatostatin-14 (250 pg/ml), the stimulatory action of exogenous insulin on L-serine transport was abolished. If endogenous insulin and somatostatin, released concurrently in response to 16.8 mmol/l D-glucose, were conveyed to the exocrine epithelium via an islet-acinar portalaxis, it is conceivable that somatostatin modulates the stimulatory action of insulin on basolateral amino acid transport in the exocrine pancreas.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00265091
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