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Role of the decrease in ionized calcium in the inhibition of insulin release by chloride-free solutions
Biochimica Et Biophysica Acta
|November 28, 1986
Summary
Replacing extracellular chloride (Cl-) with isethionate or sulfate inhibits insulin release from mouse islets. This inhibition is partly due to decreased calcium levels, but other factors also contribute depending on the chloride substitute used.
Area of Science:
- Endocrinology
- Cell Physiology
- Molecular Biology
Background:
- Extracellular chloride ions (Cl-) play a role in regulating insulin secretion.
- The precise mechanisms by which Cl- influences insulin release are not fully understood.
Purpose of the Study:
- To investigate the role of extracellular Cl- in insulin release.
- To determine the contribution of ionized calcium (Ca2+) changes to Cl--free-induced inhibition of insulin secretion.
Main Methods:
- Perifusion of mouse islets.
- Stimulation of insulin release using glucose or tolbutamide.
- Replacement of extracellular Cl- with isethionate or sulfate.
- Measurement of ionized Ca2+ concentrations.
Main Results:
- Replacement of Cl- with isethionate or sulfate reversibly inhibited insulin release.
- Isethionate and sulfate solutions decreased ionized Ca2+ by 30% and 55%, respectively.
- Preventing the fall in ionized Ca2+ only partially ameliorated the inhibition of insulin release.
Conclusions:
- Inhibition of insulin release in Cl--free solutions is not solely due to decreased ionized Ca2+.
- The extent to which Ca2+ contributes to the inhibition depends on the specific Cl- substitute used.