Three types of cytoplasmic Ca2+ oscillations in stimulated pancreatic beta-cells.
Oscillations of cytoplasmic Ca2+ (Ca2+i) involved in cell regulation have recently attracted considerable attention. In the pancreatic beta-cells an intermediate concentration of glucose (11 mM) induces large oscillations of Ca2+i with periods of 2 to 6 min. Procedures stimulating insulin secretion further, such as raising glucose to 20-30 mM or adding carbachol, ATP, theophylline, glucagon, or forskolin, often changed these oscillations into a steady increase of Ca2+i. In addition, forskolin and glucagon triggered prominent 9- to 14-s Ca2+i spikes during the intervals of increased Cai2+, whereas carbachol and ATP initiated a series of rapid spikes of decreasing magnitude and increasing duration (6-11 s). All types of oscillations depended on the presence of extracellular Ca2+i, but carbachol and ATP also induced single Cai2+ transients in the absence of the cation. The results demonstrate hitherto unknown oscillations of Ca2+i in the pancreatic beta-cell which are dependent in different ways on Ca2+ entry.
Grapengiesser
E
E
Department of Medical Cell Biology, Uppsala University, Sweden.
Gylfe
E
E
Hellman
B
B
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001572:Benzofurans; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D016257:Fura-2; D005934:Glucagon / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology*; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D008820:Mice, Obese; D051381:Rats; D013806:Theophylline / Q000494:pharmacology
D001572:Benzofurans; D005576:Colforsin; D000255:Adenosine Triphosphate; D002217:Carbachol; D005934:Glucagon; D013806:Theophylline; D000242:Cyclic AMP; D005947:Glucose; D002118:Calcium; D016257:Fura-2