Adenine nucleotide metabolism of blood platelets VI. Subcellular localization of nucleotide pools with different functions in the platelet release reaction

摘要: Abstract 1. Homogenates of washed human platelets have been fractionated on sucrose gradients, and the amounts ATP, ADP serotonin in fractions determined. 2. The bulk (90–95%) nucleotides was recovered soluble fraction, whereas majority particle-bound present a high density fraction with ATP ratio 0.6-1.1. Particle-bound also had its highest concentration these particles an 5–7. Incubation platelet-rich plasma radioactive adenosine, adenine or orthophosphate gave labeled membranes mitochondria, appeared nonradioactive. 3. When were exposed to collagen, nonradioactive released equal that granule-bound nucleotides. lost from cells suggested direct release. During release highly disappeared could be intracellularly as IMP. 4. Thrombin maximally 60% platelet ATP+ADP 0.78. About 20% without being released. 5. results can explained by assuming 3 pools platelets: One pool (60% total ATP+ADP, = 0.6−1.1 ) is stored special granules, does not participate metabolism directly extruded during reaction. A second consists presumably only (10% ATP+ADP), consumed converted third (30% ATP+ADP) cytoplasm, mitochondria unchanged equilibrium pool.