Fluorescence digital image analysis of glucose-induced [Ca2+]i oscillations in mouse pancreatic islets of Langerhans.
At intermediate glucose concentrations, [Ca2+]i (intracellular calcium) measured in single islets of Langerhans undergo oscillations that are caused by glucose-induced bursting of electrical activity. Using digital video imaging of fura-2--loaded islets, we have analyzed the spatial distribution of [Ca2+]i in response to the natural secretagogue glucose and the KATP channel blocker tolbutamide. When the glucose level is increased, [Ca2+]i first increases and then starts to oscillate with a synchronous pattern through the islet. The synchrony is maintained even during nonrhythmic oscillatory patterns. In the presence of tolbutamide, [Ca2+]i increases in all the islet regions, suggesting that the calcium signal is derived mainly from the beta-cell population. These results demonstrate that the islets behave as a functional syncytium in response to stimulatory glucose levels, canceling out heterogeneities at the single cell level.
Valdeolmillos
M
M
Instituto de Neurociencias, Universidad de Alicante, Spain.
Nadal
A
A
Soria
B
B
García-Sancho
J
J
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005947:Glucose / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008856:Microscopy, Fluorescence; D014044:Tolbutamide / Q000494:pharmacology
D014044:Tolbutamide; D005947:Glucose; D002118:Calcium