In:
Canadian Journal of Physiology and Pharmacology, Canadian Science Publishing, Vol. 70, No. S1 ( 1992-05-15), p. S64-S72
Abstract:
Spatial and temporal changes in the intracellular free Ca 2+ concentration in response to Ca 2+ influx at the cell membrane and to Ca 2+ release from intracellular organelles were studied by recording fluorescence of Ca 2+ -sensitive probes, fura 2 or indo 1, with conventional epifluorescence or confocal laser-scanning microscopy combined with recordings of Ca 2+ -dependent membrane responses in bullfrog sympathetic ganglion cells. It was found that an increase in the intracellular Ca 2+ induced by (an) action potential(s) in freshly isolated ganglion cells bathed in Ringer's solution was solely a result of Ca 2+ influx, while a rise in the intracellular Ca 2+ by Ca 2+ current in voltage-clamped cultured neurones was caused by not only Ca 2+ influx but also Ca 2+ release. This Ca 2+ release was suggested to occur by a voltage-dependent (and graded) mode of activation of a Ca 2+ -induced Ca 2+ release mechanism, explaining the lack of Ca 2+ release by action potentials (because of their short-lasting depolarization) in freshly isolated neurones. In both cases, there was an inward spread of an increase in intracellular Ca 2+ . On the other hand, all or nothing activation of Ca 2+ -induced Ca 2+ release occurred in the presence of caffeine, leading to the oscillation of Ca 2+ in the cells. Characteristics of this mode of Ca 2+ release and unique properties of drugs to block Ca 2+ release were described. Finally, the physiological significance of different types of Ca 2+ release was discussed.Key words: Ca 2+ current, Ca 2+ -induced Ca 2+ release, Ca 2+ transient, confocal microscope, bullfrog sympathetic ganglion cells.
Type of Medium:
Online Resource
ISSN:
0008-4212
,
1205-7541
Language:
English
Publisher:
Canadian Science Publishing
Publication Date:
1992
detail.hit.zdb_id:
2004356-9
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