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Scientific article
Open access
English

Calcium-induced insulin release in monolayer culture of the endocrine pancreas. Studies with ionophore A23187

Published inThe Journal of biological chemistry, vol. 250, no. 4, p. 1354-1360
Publication date1975
Abstract

The role of Ca2+ on insulin release has been studied by the use of ionophore A23187. The ionophore complexes divalent cations and permits Ca2+ entry into cells by acting as a carrier in the plasma membranes. Cultured cells obtained by enzymatic digestion of pancreases from newborn rats were studied on the 3rd day of culture. With Ca2+ in the incubation medium the ionophore induced sustained insulin release even in the absence of glucose. Optimal effects of the ionophore were observed at 3 and 10 mug per ml in the presence of 0.3 to 1.0 mM Ca-2+. Under these conditions the insulin release was greater than that caused by 16.7 mM glucose. A graded response was observed to changes in Ca-2+ concentration from 0.1 to 1.0 mM Ca-2+. Higher Ca-2+ concentrations caused a large amount of insulin to be released promptly, but the release was not sustained. Mg-2+ and Sr-2+ were not found to substitute for Ca-2+. Ba-2+ at 0.3 mM stimulated insulin release even in the absence of ionophore. Cyclic adenosine 3':5'-monophosphate was able to increase ionophore-induced insulin release. The alpha-adrenergic effect of epinephrine to inhibit insulin release was not observed in the presence of Ca-2+ and the ionophore, and a stimulatory effect of epinephrine was seen. This unusual stimulatory effect of epinephrine was blocked by propranolol indicating a beta-adrenergic mechanism for epinephrine. It is concluded that Ca-2+, which plays an essential role in the stimulus-secretion coupling, can alone initiate and cause sustained insulin release.

Keywords
  • Animals
  • Anti-Bacterial Agents/pharmacology
  • Antibodies
  • Barium/pharmacology
  • Calcium/pharmacology
  • Carboxylic Acids/pharmacology
  • Cells, Cultured
  • Cyclic AMP/pharmacology
  • Epinephrine/pharmacology
  • Glucose/pharmacology
  • Insulin/metabolism
  • Islets of Langerhans/drug effects/metabolism
  • Magnesium/pharmacology
  • Propranolol/pharmacology
  • Rats
  • Strontium/pharmacology
Citation (ISO format)
WOLLHEIM, Claes et al. Calcium-induced insulin release in monolayer culture of the endocrine pancreas. Studies with ionophore A23187. In: The Journal of biological chemistry, 1975, vol. 250, n° 4, p. 1354–1360.
Main files (1)
Article (Published version)
accessLevelPublic
Identifiers
  • PID : unige:40545
  • PMID : 163251
ISSN of the journal0021-9258
464views
178downloads

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