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Intracellular calcium buffering shapes calcium oscillations in Xenopus melanotropes.
- Source :
-
Pflugers Archiv : European journal of physiology [Pflugers Arch] 2001 Nov; Vol. 443 (2), pp. 250-6. - Publication Year :
- 2001
-
Abstract
- The pituitary melanotrope cell of Xenopus laevis displays cytosolic Ca2+ oscillations that arise for the interplay between the burst-like openings of voltage-operated Ca2+ channels and Ca2+-extrusion mechanisms. We have previously shown that Ca2+-extrusion rates increase with increases in [Ca2+]i, suggesting that Ca2+ itself plays a role in shaping the Ca2+ oscillations. The purpose of the present study was to test this hypothesis by manipulating the intracellular Ca2+ buffering capacity of the cell and determining the consequences of such manipulations for the shape of the Ca2+ oscillations. We manipulated the cytosolic buffering capacity by loading the fast Ca2+ chelator BAPTA into cells. During loading the [Ca2+]i was dynamically imaged with confocal laser scanning microscopy. The basal [Ca2+]i was reduced with BAPTA loading and this reduction was associated with lower Ca2+-extrusion rates, a broadening of the Ca2+ oscillations and declined oscillation frequencies. Short loading periods of the buffer led to new, stable patterns of Ca2+ signaling and to reduced but stable levels of peptide secretion. We propose that the cytosolic Ca2+ buffer capacity, and thus by inference the profile of intracellular Ca2+ buffering proteins, is an important factor in setting the frequency and shape of Ca2+ oscillations.
- Subjects :
- Animals
Buffers
Chelating Agents administration & dosage
Chelating Agents pharmacology
Egtazic Acid administration & dosage
Egtazic Acid pharmacology
Oscillometry
Peptides metabolism
Pituitary Gland cytology
Time Factors
Xenopus laevis
Calcium metabolism
Egtazic Acid analogs & derivatives
Intracellular Membranes metabolism
Melanocyte-Stimulating Hormones metabolism
Pituitary Gland metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0031-6768
- Volume :
- 443
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- Pflugers Archiv : European journal of physiology
- Publication Type :
- Academic Journal
- Accession number :
- 11713651
- Full Text :
- https://doi.org/10.1007/s004240100680