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unige:35655 
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Oscillations of cytosolic free calcium in bombesin-stimulated HIT-T15 cells |
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| Authors | ||
| Published in | Cell Calcium. 1996, vol. 19, no. 6, p. 535-46 | |
| Abstract | The mechanism underlying the generation of cytosolic free Ca2+ ([Ca2+]i) oscillations by bombesin, a receptor agonist activating phospholipase C, in insulin secreting HIT-T15 cells was investigated. At 25 microM, 61% of cells displayed [Ca2+]i oscillations with variable patterns. The bombesin-induced [Ca2+]i oscillations could last more than 1 h and glucose was required for maintaining these [Ca2+]i fluctuations. Bombesin-evoked [Ca2+]i oscillations were dependent on extracellular Ca2+ entry and were attenuated by membrane hyperpolarization or by L-type Ca2+ channel blockers. These [Ca2+]i oscillations were apparently not associated with fluctuations in plasma membrane Ca2+ permeability as monitored by the Mn2+ quenching technique. 2,5-di-(tert-butyl)-1,4-benzohydroquinone (tBuBHQ) and 4-chloro-m-cresol, which interfere with intracellular Ca2+ stores, respectively, by inhibiting Ca(2+)-ATPase of endoplasmic reticulum and by affecting Ca(2+)-induced Ca2+ release, disrupted bombesin-induced [Ca2+]i oscillations. 4-chloro-m-cresol raised [Ca2+]i by mobilizing an intracellular Ca2+ pool, an effect not altered by ryanodine. Caffeine exerted complex actions on [Ca2+]i. It raised [Ca2+]i by promoting Ca2+ entry while inhibiting bombesin-elicited [Ca2+]i oscillations. Our results suggest that in bombesin-elicited [Ca2+]i oscillations in HIT-T15 cells: (i) the oscillations originate primarily from intracellular Ca2+ stores; and (ii) the Ca2+ influx required for maintaining the oscillations is in part membrane potential-sensitive and not coordinated with [Ca2+]i oscillations. The interplay between intracellular Ca2+ stores and voltage-sensitive and voltage-insensitive extracellular Ca2+ entry determines the [Ca2+]i oscillations evoked by bombesin. | |
| Keywords | Animals — Biological Clocks/drug effects/physiology — Bombesin/pharmacology — Caffeine/pharmacology — Calcium/analysis/metabolism — Calcium Channel Blockers/pharmacology — Calcium Channels/drug effects/metabolism — Calcium-Transporting ATPases/antagonists & inhibitors — Cell Line — Central Nervous System Stimulants/pharmacology — Chelating Agents/pharmacology — Circadian Rhythm — Cresols/pharmacology — Cricetinae — Cytosol/drug effects/metabolism — Diazoxide/pharmacology — Egtazic Acid/pharmacology — Fura-2/pharmacology — Glucose/pharmacology — Hydroquinones/pharmacology — Membrane Potentials/drug effects — Ryanodine/pharmacology — Verapamil/pharmacology | |
| Identifiers | PMID: 8842521 | |
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| Citation (ISO format) | LI, Guodong, WOLLHEIM, Claes, PRALONG, William. Oscillations of cytosolic free calcium in bombesin-stimulated HIT-T15 cells. In: Cell Calcium, 1996, vol. 19, n° 6, p. 535-46. https://archive-ouverte.unige.ch/unige:35655 |
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