Cytosolic Ca2+ oscillations by gastrin releasing peptide in single HIT-T15 cells.
In single, superfused, FURA-2AM loaded insulin producing HIT-T15 cells, gastrin releasing peptide (GRP) induced a peak in cytoplasmnic Cu2+ ([Ca2+]i) followed by a sustained (high GRP concentrations) or oscillatory (low GRP concentrations) [Ca2+]i pattern. The GRP (25-50 microM)-induced [Ca2+]i oscillations ceased upon removal of glucose or addition of thapsigargin (1 microM), EGTA (2 mM), or diazoxide (200 microM), whereas nifedipine (10 microM) reduced their amplitude (by 35%). Both protein kinase C (PKC)-activation or PKC-inhibition disrupted GRP induced [Ca2+]i oscillations. GRP induced [Ca2+]i oscillations in insulin producing cells therefore rely on intracellular Ca2+ mobilization, voltage-dependent and voltage-independent Ca2+ entry mechanisms and the integrity of protein kinase C.
Karlsson
S
S
Department of Medicine, Lund University, Malmö University Hospital, Sweden.
Ahrén
B
B
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism*; D003981:Diazoxide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004533:Egtazic Acid / Q000494:pharmacology; D019886:Gastrin-Releasing Peptide / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology; D015640:Ion Channel Gating; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D009543:Nifedipine / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
D002121:Calcium Channel Blockers; D004533:Egtazic Acid; D019284:Thapsigargin; D019886:Gastrin-Releasing Peptide; D011493:Protein Kinase C; D009543:Nifedipine; D005947:Glucose; D013755:Tetradecanoylphorbol Acetate; D003981:Diazoxide; D002118:Calcium