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PubMed · 2850037

[A decrease in the stimulated level of free intracellular calcium in thrombocytes during refractoriness].

E Ia Pozin·E G Popov·I Iu Gavrilov·Z A Gabbasov·S N Krotov
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Abstract

The concentration of free intracellular calcium (Ca.f) was determined in ADP-stimulated platelets. Free calcium was measured by the multichannel method using fluorescent probe indo 1. In the presence of extracellular calcium, ADP induced a rapid reversible increase in Ca.f followed by reversible platelet aggregation. The second addition of ADP also induced increase in Ca.f and platelet aggregation, which were of lesser magnitude (platelet refractoriness). Without extracellular calcium, ADP also produced an increase in Ca.f. In this case the second addition of ADP also induced considerably less increase in Ca.f.

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Adenosine DiphosphateAnimalsBlood PlateletsCalciumCyclic AMPCytoplasmFluorescent DyesPlatelet AggregationRabbitsStimulation, ChemicalComparative StudyEnglish AbstractJournal Article

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E Ia Pozin, E G Popov, I Iu Gavrilov, Z A Gabbasov, S N Krotov. 1988. [A decrease in the stimulated level of free intracellular calcium in thrombocytes during refractoriness].. https://pubmed.ncbi.nlm.nih.gov/2850037/

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Adenosine Diphosphate↗
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Tubulin, widely recognized as a GTP/GDP-binding protein, has been isolated in its polymerized state from rat PC12 cells and embryonic chick dorsal root ganglion neurons by Triton X-100 detergent extraction of the cytoskeletal fraction. Perchloric acid extraction and deproteinization of this fraction permitted subsequent analysis of nucleotide identity and content by high performance liquid chromatography. PC12 cells grown in the absence of nerve growth factor (NGF) contained ADP, ATP, GDP, and GTP at levels consistent with the actin and tubulin content of the cytoskeletal fraction. Microtubules from PC12 cells cultured in the presence of NGF contain an additional nucleotide that we have identified as dGTP. Analysis of whole cell nucleotide extracts from PC12 cells grown in the absence or presence of NGF revealed no evidence for the presence of dGTP at 4 and 14 days, respectively. We have determined that embryonic chick dorsal root ganglion neurons also contain this deoxyribonucleotide, and we found virtually no ADP or ATP in the extracted dorsal root ganglion cytoskeletal fraction. On the basis of metabolic labeling studies with [14C] guanine, we have inferred that the presence of dGTP in NGF-treated PC12 cells probably arises either from binding to the nonexchangeable nucleotide site of tubulin undergoing dynamic assembly/disassembly or from binding to the exchangeable site of tubulin subsequently incorporated into highly stabilized microtubules.

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PubMed1992

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Adenosine Diphosphate↗