Adenine nucleotide storage and secretion in platelets as studied by 31P nuclear magnetic resonance.

AUTOR(ES)

Ugurbil, K

RESUMO

Suspensions of human and pig blood platelets have been studied by 31P NMR at 145.7 MHz and by chemical and radiochemical determination of nucleotide levels. In both types of platelets the cytoplasmic nucleotide pool, which was prelabeled by incubation with [14C]adenine, was selectively reduced by addition of H2O2/NaN3 or 2-deoxyglucose/antimycin A. After the reduction of cytoplasmic ATP in human platelets, the 31P NMR spectra showed an almost complete loss of the nucleoside di- and triphosphate resonances at temperatures examined (4--50 degrees C), indicating that only the cytoplasmic nucleotides had been observed, with no detectable contributions from the granular ATP, ADP, and pyrophosphate. Slow tumbling of the granular nucleotides, possibly due to aggregation, is the probable explanation of their undetectability at 145.7 MHz. Similar experiments showed that in pig platelets, granular ATP and ADP were not detected by 31P NMR at 4 degrees C but were observed at higher temperatures, indicating that aggregation may be occurring at the lower temperatures. Upon thrombin stimulation of human platelets, the NMR spectra and the chemical and radioactivity analyses showed that the granular adenylates and pyrophosphate were secreted, and that cytoplasmic ATP levels were appreciably reduced.

Documentos Relacionados

• The effects of pregnancy and parturition on phosphorus metabolites in rat uterus studied by 31P nuclear magnetic resonance.
• Measurement of the internal pH of yeast spores by 31P nuclear magnetic resonance.
• Decreased energy requirement of toad retina during light adaptation as demonstrated by 31P nuclear magnetic resonance.
• Phosphate metabolites in lymphoid, Friend erythroleukemia, and HeLa cells observed by high-resolution 31P nuclear magnetic resonance.
• Phosphorous compounds studied by 31P nuclear magnetic resonance spectroscopy in the taenia of guinea-pig caecum.