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Oscillations of cytosolic free calcium in bombesin-stimulated HIT-T15 cells
- Source :
- Cell Calcium, Vol. 19, No 6 (1996) pp. 535-46
- Publication Year :
- 1996
- Publisher :
- Elsevier BV, 1996.
-
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.
- Subjects :
- Calcium Channel Blockers/pharmacology
Calcium-Transporting ATPases/antagonists & inhibitors
Physiology
Fura-2/pharmacology
Membrane Potentials/drug effects
Membrane Potentials
Caffeine/pharmacology
Ryanodine/pharmacology
Cresols
chemistry.chemical_compound
Cytosol
Cricetinae
Egtazic Acid
Chelating Agents
ddc:616
Cresols/pharmacology
Ryanodine
Ryanodine receptor
Bombesin
Calcium Channel Blockers
Biological Clocks/drug effects/physiology
Glucose/pharmacology
Circadian Rhythm
Cell biology
Calcium Channels/drug effects/metabolism
Egtazic Acid/pharmacology
Fura-2
Intracellular
Calcium/analysis/metabolism
Calcium-Transporting ATPases
Biology
Cell Line
Biological Clocks
Caffeine
Extracellular
Animals
Channel blocker
Verapamil/pharmacology
Molecular Biology
Hydroquinones/pharmacology
Endoplasmic reticulum
Diazoxide
Cell Biology
Membrane hyperpolarization
Diazoxide/pharmacology
Hydroquinones
Cytosol/drug effects/metabolism
Glucose
Verapamil
chemistry
Central Nervous System Stimulants/pharmacology
Calcium
Central Nervous System Stimulants
Calcium Channels
Bombesin/pharmacology
Chelating Agents/pharmacology
Subjects
Details
- ISSN :
- 01434160
- Volume :
- 19
- Database :
- OpenAIRE
- Journal :
- Cell Calcium
- Accession number :
- edsair.doi.dedup.....1f4022bdc85aa0e7566044d9c4efdf5b