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Scientific article
Open access
English

Oscillations of cytosolic free calcium in bombesin-stimulated HIT-T15 cells

Published inCell calcium, vol. 19, no. 6, p. 535-546
Publication date1996
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
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. 535–546. doi: 10.1016/s0143-4160(96)90063-9
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Article (Published version)
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Identifiers
ISSN of the journal0143-4160
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