ISSN:
1432-0428
Keywords:
Isolated rat islets
;
phosphate flush
;
glucose
;
α-ketoisocaproate
;
leucine
;
glutamine
;
lactate
;
quinine
;
menadione
;
antimycin A
;
barium
;
potassium
;
bicarbonate
;
calcium
;
theophylline
;
tolbutamide
;
arginine
;
anoxia
;
cyclic AMP
;
insulin release
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Above a threshold of 3.0–4.2 mmol/l, D-glucose provoked a transient increase in 32P fractional outflow rate from rat pancreatic islets prelabelled with 32P-orthophosphate. Nutrients which stimulate insulin release in the absence of glucose, α-ketoisocaproate and L-leucine, also provoked a phosphate flush. No flush occurred in islets exposed to non-insulinotropic nutrients (L-glutamine and L-lactate) or non-nutrient secretagogues (arginine, tolbutamide, theophylline). A late increase in 32P fractional outflow rate was observed in Ca2+ deprived islets stimulated with BaCl2 and theophylline. The occurrence of a phosphate flush did not appear to be attributable to changes in insulin release, cyclic AMP content, membrane polarisation, K+ conductance, or reduced pyridine nucleotide content. The 32P response to glucose was slightly decreased in the absence of extracellular Ca2+ or HCO3 -, markedly impaired in the absence of K+, and virtually abolished in the presence of menadione (10 μmol/l). It is proposed that the occurrence of a phosphate flush is linked to the metabolism of nutrient secretagogues, possibly via an increase in O2 uptake and the production rate of NAD(P)H and ATP.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00281826
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