Isolation and properties of human platelet mitochondria

Abstract

A mitochondrial fraction of human platelets that exhibited respiration coupled to ADP utilization was isolated. These activities were sensitive to classical inhibitors of mitochondrial respiration and oxidative phosphorylation. Pyridine nucleotide linked substrates were oxidized at low rates (4 to 7 natoms/min/mg), but succinate and a glycerophosphate were oxidized more rapidly (16 and 38 natoms/min/mg, respectively). Difference spectra showed the presence of the mitochondrial respiratory chain cytochromes, c1 + c,b, and a + a3. Electron micrographs revealed the presence of intact mitochondria with well preserved outer membranes, as well as various a granules. There appeared to be no qualitative differences between these human platelet mitochondria and pig platelet mitochondra isolated by the same procedure.