Stimulation of phosphate uptake in human platelets by thrombin and collagen. Changes in specific /sup 32/P labeling of metabolic ATP and polyphosphoinositides

Journal Article · Mon May 25 00:00:00 EDT 1987 · J. Biol. Chem.; (United States)

OSTI ID:6332649

Verhoeven, A J; Tysnes, O B; Horvli, O; Cook, C A; Holmsen, H

The uptake of (/sup 32/P)phosphate by human, gel-filtered blood platelets and its incorporation into cytoplasmic ATP and polyphosphoinositides was studied. In unstimulated platelets, uptake was Na+o-dependent and saturable at approximately 20 nmol/min/10(11) cells with a half-maximal rate at 0.5 mM extracellular phosphate. Upon stimulation with thrombin or collagen, net influx of (/sup 32/P)Pi was accelerated 5- to 10-fold. With thrombin, (/sup 32/P)Pi efflux was also increased. After the first 2 min, efflux exceeded influx, resulting in the net release of (/sup 32/P)Pi from the platelets. Since the stimulus-induced burst in (/sup 32/P)Pi uptake paralleled the secretory responses, it might be an integral part of stimulus-response coupling in platelets. The stimulus-induced burst in net (/sup 32/P)Pi uptake led to an enhanced labeling of metabolic ATP, which was already detectable at 5 s after stimulation with thrombin. Concomitantly, the incorporation of (/sup 32/P)Pi into phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate was accelerated. The thrombin-induced increase in specific /sup 32/P radioactivity of cytoplasmic ATP fully accounted for the simultaneous increase in specific /sup 32/P radioactivity of these phosphoinositides. In studying the extent of /sup 32/P labeling of phosphorylated compounds in response to a cellular stimulus, it is therefore essential to measure the effect of the stimulus on the specific radioactivity of cytoplasmic ATP.

• Research Organization: Univ. of Bergen, Norway
• OSTI ID: 6332649
• Journal Information: J. Biol. Chem.; (United States), Vol. 15
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ATP
LABELLING
COLLAGEN
BIOCHEMICAL REACTION KINETICS
PHOSPHATES
UPTAKE
PHOSPHOLIPIDS
THROMBIN
BLOOD PLATELETS
CYTOPLASM
PHOSPHORUS 32
SODIUM
TRACER TECHNIQUES
ALKALI METALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CELL CONSTITUENTS
COAGULANTS
DAYS LIVING RADIOISOTOPES
DRUGS
ELEMENTS
ENZYMES
ESTERS
HEMATOLOGIC AGENTS
HEMOSTATICS
HYDROLASES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
LIPIDS
MATERIALS
METALS
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
OXYGEN COMPOUNDS
PEPTIDE HYDROLASES
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
SCLEROPROTEINS
SERINE PROTEINASES
550201* - Biochemistry- Tracer Techniques