Linked Life Data

7854327

Source:http://linkedlifedata.com/resource/pubmed/id/7854327

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1995-3-15
pubmed:abstractText
The magnesium buffer coefficient (BMg) was calculated for BC3H-1 cells from the rise in cytosolic Mg2+ activity observed when magnesium was released from ATP after iodoacetate (IAA) and NaCN treatment. The basal cytosolic Mg2+ activity (0.54 +/- 0.1 mM) measured with mag-fura-2 doubled when 4.54 mM magnesium was liberated from ATP: BMg was 12.9 indicating that a 1 mM increase in Mg2+ activity requires an addition of about 13 mM magnesium. The accuracy of this value depends on these assumptions: (a) all of the magnesium released from ATP stayed in the cells; (b) the rise in Mg2+ was not secondary to pH-induced changes in BMg; (c) mag-fura-2 measured Mg2+ and not Ca2+; and (d) the accuracy of the mag-fura-2 calibration. Total magnesium did not change in response to IAA/CN treatment, thus the change in Mg2+ activity reflected a redistribution of cell magnesium. pH changes induced by NH4Cl pulse and removal had little effect on Mg2+ activity and the changes were slower than and opposite to pH-induced changes in Ca2+ activity measured by fura-2. Ca2+ responses were temporally uncoupled from Mg2+ responses when the cells were treated with IAA only and in no cases did Ca2+ levels rise above 1 microM, showing that the mag-fura-2 is responding to Mg2+. Additional studies demonstrated that approximately 90% of the mag-fura-2 signal was cytosolic in origin. The remaining non-diffusible mag-fura-2 either was bound to cytosolic membranes or sequestered in organelles with the fluorescence characteristics of the Mg2(+)-complexed form, even when cytosolic free Mg2+ activity was approximately 0.5 mM. This bound mag-fura-2 would appear to increase the Kd and thus clearly limits the accuracy of our estimmate for BMg. Despite this limitation, we demonstrate that Mg2+ is tightly regulated in face of large changes in extracellular Mg2+, and that interplay observed between pH, Ca2+ and Mg2+ activities strongly supports the hypothesis that these factors interact through a shared buffer capacity of the cell.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/2-(2-(5-carboxy)oxazole)-5-hydroxy-6..., http://linkedlifedata.com/resource/pubmed/chemical/Adenosine Triphosphate, http://linkedlifedata.com/resource/pubmed/chemical/Ammonium Chloride, http://linkedlifedata.com/resource/pubmed/chemical/Buffers, http://linkedlifedata.com/resource/pubmed/chemical/Digitonin, http://linkedlifedata.com/resource/pubmed/chemical/Fluorescent Dyes, http://linkedlifedata.com/resource/pubmed/chemical/Fura-2, http://linkedlifedata.com/resource/pubmed/chemical/Iodoacetates, http://linkedlifedata.com/resource/pubmed/chemical/Iodoacetic Acid, http://linkedlifedata.com/resource/pubmed/chemical/Magnesium, http://linkedlifedata.com/resource/pubmed/chemical/Phloretin, http://linkedlifedata.com/resource/pubmed/chemical/Sodium Cyanide
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0300-8177
pubmed:author
pubmed:issnType
Print
pubmed:day
13
pubmed:volume
136
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
11-22
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Determination of cytosolic Mg2+ activity and buffering in BC3H-1 cells with mag-fura-2.
pubmed:affiliation
Department of Pharmacology and Toxicology, School of Medicine, Wright State University, Dayton, Ohio 45435.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't