Ca2+ dynamics in rat pancreatic AR-42J and AR-IP cells.
Spatiotemporal change of the cytosolic free Ca2+ concentration ([Ca2+]i) in response to a variety of secretagogues was examined in rat pancreatoma AR-42J and AR-IP cells by microspectroflurometry and digital imaging microscopy after loading with fura-2. In the presence of external Ca2+, carbachol, CCK-OP (cholecystokinin-octapeptide), gastrin, norepinephrine or high K+ evoked a large transient increase in [Ca2+]i in AR-42J cells which declined to a sustained level before slowly declining towards the resting level. In the absence of external Ca2+, a transient increase in [Ca2+]i were evoked by all the ligands except for high K+ stimulation, which declined rapidly towards the resting level. The [Ca2+]i increase caused by carbachol and high K+ treatment was inhibited by muscarinic receptor antagonist, atropine, and by L-type Ca2+ channel blocker, nifedipine, respectively. The transient [Ca2+]i increase induced by gastrin stimulation was not blocked by Ca2+ channel blocker, lanthanum. In the AR-IP cells, which are non-differentiated pancreatoma cell line, all stimulations including high K+ treatment have failed to evoke [Ca2+]i response. These intracellular Ca2+ mobilizations in response to ligands in AR-42J cells were displayed by digital imaging microscopy. From these results we conclude that AR-42J cells has an alpha-adrenergic receptor, in addition to muscarinic acetylcholine receptor, CCK-OP receptor, gastrin receptor and voltage dependent Ca2+ channel. In marked contrast, AR-IP cells have neither any hormone receptor for the above ligands nor voltage dependent Ca2+ channel.
Funai
T
T
Department of Physiology, Kansai Medical University, Osaka, Japan.
Yodozawa
S
S
Tashiro
Y
Y
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002766:Cholecystokinin / Q000494:pharmacology; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D016257:Fura-2; D007091:Image Processing, Computer-Assisted; D015759:Ionomycin / Q000494:pharmacology; D007811:Lanthanum / Q000494:pharmacology; D008856:Microscopy, Fluorescence / Q000379:methods; D009543:Nifedipine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D009994:Osmolar Concentration; D010179:Pancreas / Q000378:metabolism*; D051381:Rats; D013050:Spectrometry, Fluorescence
D015759:Ionomycin; D007811:Lanthanum; D001285:Atropine; D002217:Carbachol; D002766:Cholecystokinin; D009543:Nifedipine; D002118:Calcium; D016257:Fura-2; D009638:Norepinephrine