Insulin-secreting INS-1 cells generate a novel type of poorly synchronized Ca2+ transients.
Pancreatic beta-cells have an intrinsic oscillatory Ca2+ activity supposed to be synchronized among the islets by cytoplasmic Ca2+ transients elicited by nonadrenergic, noncholinergic (NANC) neurons. To improve the understanding of this process, the cytoplasmic Ca2+ concentration ([Ca2+]i) was measured in two insulin-releasing cell lines using dual wavelength microfluorometry and the indicator fura-2. INS-1 cells but not RINm5F cells were found to generate transients of [Ca2+]i in the presence of the Ca2+ channel blocker methoxyverapamil. These transients differed from those occurring in native beta-cells persisting in the presence of thapsigargin or during prolonged exposure to ATP. Moreover, the [Ca2+]i transients were poorly synchronized whether or not the INS-1 cells had physical contact. If appearing in native beta-cells, the type of [Ca2+]i transients now observed may interfere with the coordination of the beta-cell rhythmicity evoked by NANC neurons.
Dorff
Gernot
G
Department of Medical Cell Biology, Uppsala University, Biomedicum, Box 571, SE-751 23 Uppsala, Sweden.
Grapengiesser
Eva
E
Hellman
Bo
B
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D020013:Calcium Signaling; D002460:Cell Line; D005934:Glucagon / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D008820:Mice, Obese; D010507:Periodicity; D019284:Thapsigargin / Q000494:pharmacology
D007328:Insulin; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D005934:Glucagon