[The mechanism of inhibition of the increase in intracellular calcium concentration by the islet amyloid polypeptide in high glucose-stimulated INS-1 cells].

Academic Article

Abstract

  • To explore the potential mechanism of the inhibition of increased intracellular free calcium concentration ([Ca2+]i) by short-term exposure to the islet amyloid polypeptide (IAPP) in high glucose-stimulated pancreatic β cells. The pancreatic β cells were loaded with calcium sensitive fluorescent indicator Fluo-4/AM. The fluorescence intensity, which represented [Ca2+]i, was measured in time by laser scanning confocal microscope before and after stimulated by glucose, KCl, caffeine and carbachol. The fluorescence intensity F/F0 in INS-1 cells, increased to about 2 folds after glucose stimulation. After the exposure to the IAPP with different concentration, the fluorescence intensity F/F0 was decreased slightly in the pretreated cells by 16.7 mmol/L glucose with 0.5 μmol/L IAPP. However, after the pretreatment of IAPP with the concentration of 1.0, 5.0, 10.0 μmol/L, the fluorescence intensity F/F0 showed a dose-dependent decrease with statistical difference. The fluorescence intensity F/F0 in the cells increased rapidly in a peak pattern after the stimulation of 30 mmol/L KCl. But with the pretreatment of 10.0 μmol/L IAPP, the fluorescence intensity F/F0 decreased with statistical difference. With 20 mmol/L caffeine and 100 μmol/L carbachol which stimulated Ca2+ release respectively from internal ryanodine receptor (RYR) and inositol triphosphate (IP3) Ca2+ storage, the fluorescence intensity F/F0 curve presented a peak pattern. After 10 μmol/L IAPP pretreatment, the fluorescence intensity F/F0 showed no statistical difference from the control group. The short-term effect of IAPP on pancreatic β cells has no influence on the caffeine and carbachol stimulated Ca2+ release from endoplasmic reticulum RYR and IP3 Ca2+ storage. The inhibition of calcium increase in INS-1 cells by short-term exposure to IAPP may mainly via inhibiting the voltage-gated L-calcium channels with intact release capacity of Ca2+ storage.
  • Author List

  • Chen YY; Zhu TH; Liu RM; He BJ; Zhao X; Wang YZ; Li DQ; Xu Y
  • Start Page

  • 407
  • End Page

  • 411
  • Volume

  • 52
  • Issue

  • 5