PMID: 8939357Oct 1, 1996Paper

Spatial gradients of cytosolic calcium concentration in neurones during paradoxical activation by calcium

Cell Calcium
Stephen BolsoverP B Guthrie

Abstract

4-Br-A23187 caused a calcium influx into chick sensory neurones and raised cytosolic calcium from a rest level of 97 +/- 7 nM to a peak of 296 +/- 30 nM. Despite the continued presence of ionophore, however, cytosolic calcium concentrations then fell. After 30 min in ionophore, cytosolic calcium concentration had returned to 105 +/- 5 nM, not significantly different from the value before ionophore addition. The permeability of the plasmalemma to divalent cations, as estimated by the manganese quench technique, was no lower at 30 min than at the peak of the cytosolic calcium transient. Thus the fall of calcium from its peak was not due to a slowing of calcium influx, but was due to an upregulation of mechanisms that remove calcium from the cytosol- an upregulation that persists even though cytosolic calcium has apparently returned to pre-stimulus levels. We used a novel fixed slit confocal microscope to examine the calcium concentration profile close to the plasmalemma. We found that after 25-30 min ionophore treatment, calcium concentration was elevated only in the cytoplasm within 1 micron of the plasmalemma. A maintained, elevated calcium under the plasmalemma can help explain the phenomenon of paradoxical activation seen in ...Continue Reading

References

Feb 1, 1986·Cell Calcium·J W Putney
Jun 1, 1989·Molecular and Cellular Endocrinology·R W HollD A Leong
Feb 26, 1988·Science·D L Alkon, H Rasmussen
Feb 24, 1994·Nature·F A al-MohannaS R Bolsover
Oct 22, 1993·Cell·J W Putney, G S Bird
Apr 1, 1989·The Biological Bulletin·Colin D McCaig

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Citations

Jun 17, 1998·The Journal of Physiology·A A Selyanko, J A Sim
Apr 7, 2020·Platelets·M E Lopes-PiresN Pugh
Jul 11, 1998·Journal of Neurophysiology·D Murchison, W H Griffith

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