Heterogeneous changes in [Ca2+]i induced by glucose, tolbutamide and K+ in single rat pancreatic B cells

Cell Calcium. 1991 Sep;12(8):577-86. doi: 10.1016/0143-4160(91)90076-q.

Abstract

The effects of glucose, tolbutamide and K+ on cytosolic free Ca2+ ([Ca2+]i) in single rat pancreatic B cells were examined using Fura-2 and dual wavelength microfluorimetry. At basal glucose concentration (2.8 mM), about half of the cells were found to display spontaneous Ca2+ oscillations. Glucose (greater than or equal to 11.1 mM), tolbutamide (greater than or equal to 50 microM) and K+ (50 mM) induced rises in [Ca2+]i that could be inhibited by the Ca2+ channel blocker D600. The pattern of response and the sensitivity to the secretagogues were characterized by a marked heterogeneity. The majority of the cells responded to glucose and tolbutamide by a progressive increase in [Ca2+]i onto which sinusoidal oscillations were superimposed. The periodicity of these oscillations was about 2.5/min. Occasionally, some cells displayed slow and major waves in Ca2+ levels (about 0.2/min). None of the cells responded to glucose by displaying an initial decrease in [Ca2+]i. Likewise, the sugar failed to decrease [Ca2+]i in the absence of extracellular Ca2+. The present study shows that, despite a large heterogeneity of the response, the majority of the pancreatic B cells respond to different secretagogues by displaying fast [Ca2+]i oscillations that are reminiscent of the bursts of electrical activity recorded in B cells.

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Cells, Cultured
  • Cytophotometry
  • Cytosol / metabolism
  • Dose-Response Relationship, Drug
  • Fluorescent Antibody Technique
  • Fura-2
  • Glucose / pharmacology*
  • Islets of Langerhans / cytology
  • Islets of Langerhans / drug effects
  • Islets of Langerhans / metabolism*
  • Potassium / pharmacology*
  • Rats
  • Tolbutamide / pharmacology*

Substances

  • Tolbutamide
  • Glucose
  • Potassium
  • Calcium
  • Fura-2