Relationship between insulin release and /sup 65/zinc efflux from rat pancreatic islets maintained in tissue culture

Journal Article · Thu Mar 01 04:00:00 EST 1984 · Diabetes; (United States)

OSTI ID:6848594

Formby, B; Schmid-Formby, F; Grodsky, G M

In short-term batch-incubation or perfusion experiments, we studied insulin release and associated /sup 65/Zn efflux from rat pancreatic islets loaded with /sup 65/Zn by 24-h tissue culture in low-glucose medium. The fractional basal insulin release and /sup 65/Zn efflux were 0.4% and 3% of total content/h/islet, respectively. Thus, basal /sup 65/Zn efflux was much greater than that to be accounted for if zinc was released proportionally with insulin release only; extragranular zinc flux was suggested. Two millimolar glucose, with or without 1 mM 3-isobutyl-1-methylxanthine (IBMX), affected neither insulin release nor associated /sup 65/Zn efflux. Twenty-five millimolar glucose produced a significant threefold increase in insulin release above baseline, but somewhat decreased /sup 65/Zn efflux at marginal significance. Glucose (25 mM) plus 1 mM IBMX provoked a high increase in insulin release and an associated 30% increase in fractional /sup 65/Zn efflux over basal. Calculations based on previous estimations of /sup 65/Zn distribution and equilibrium with islet zinc indicated that molar zinc efflux was more than sufficient to account for a 2-zinc-insulin hexamer. L-Leucine (2 or 20 mM) plus 1 mM IBMX caused far greater /sup 65/Zn efflux for the amount of insulin released, indicating additional /sup 65/Zn mobilization not directly related to insulin secretion. To evaluate /sup 65/Zn efflux during inhibited insulin secretion, batch incubations were performed in 100% D/sub 2/O or at 27 degrees C, conditions that inhibited insulin release stimulated by high glucose plus IBMX. These agents decreased the /sup 65/Zn efflux far below the basal value (35% and 50%, respectively) and greater than could be accounted for by the attendent inhibition of insulin secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

• Research Organization: Metabolic Research Unit, University of California, San Francisco
• OSTI ID: 6848594
• Journal Information: Diabetes; (United States), Journal Name: Diabetes; (United States) Vol. 33:3; ISSN DIAEA
• Country of Publication: United States
• Language: English

Related Subjects

550201 -- Biochemistry-- Tracer Techniques
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59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AROMATICS
AZAARENES
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
CORRELATIONS
DAYS LIVING RADIOISOTOPES
DEUTERIDES
DEUTERIUM COMPOUNDS
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
ENDOCRINE GLANDS
EVEN-ODD NUCLEI
GLANDS
HETEROCYCLIC COMPOUNDS
HORMONES
HYDROGEN COMPOUNDS
HYDROGEN DEUTERIDE
INSULIN
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANS
PANCREAS
PEPTIDE HORMONES
PURINES
RADIOISOTOPES
RATS
RODENTS
SECRETION
TRACER TECHNIQUES
UPTAKE
VERTEBRATES
XANTHINES
ZINC 65
ZINC ISOTOPES