D. Mercan et Wj. Malaisse, PANCREATIC-ISLET B-CELL INDIVIDUAL VARIABILITY RATHER THAN SUBPOPULATION HETEROGENEITY, Molecular and cellular endocrinology, 118(1-2), 1996, pp. 163-171
Isolated rat pancreatic islet B-cells loaded with the Ca2+-sensitive f
luorochrome Fluo-3 were examined by single-step flow cytometry at incr
easing concentrations of D-glucose (1.0 to 20.0 mM). The near forward
scatter of light was unaffected by changes in hexose concentration. Th
e Fluo-3 fluorescent signal slightly decreased when the glucose concen
tration was raised from 1.0 to 5.0 mM, and progressively increased at
higher hexose concentrations. The fluorescence attributable to endogen
ous NAD(P)H increased dramatically throughout the full range of D-gluc
ose concentration, with a typical sigmoidal concentration-response rel
ationship. No evidence for a bimodal frequency distribution of these v
ariables was found, whether at low or high D-glucose concentrations. T
he dispersion of individual NAD(P)H measurements, as judged by either
their coefficient of variation or the height of their modal peak, was
less pronounced al high than al low D-glucose concentrations. These fi
ndings document vastly different concentration-response relationships
for metabolic and ionic variables in glucose-stimulated B-cells. They
confirm that all B-cells do not display an identical behavior, but arg
ue against the existence of subpopulation heterogeneity in their respo
nsiveness to D-glucose.