Enzyme studies on white blood cells and blood platelets. V. Dehydrogenase activity

Leukocyte Mitochondria: Function and Biogenesis

“…Thus succinate dehydro genase (EC 1.3.9.9.1) was demonstrated early in mixed leukocyte-platelet suspensions of horse blood [73], Aconitate hydratase (EC 4.2.1.3) activity was found in human leukocyte homogenates by Tanaka and Valentine [70]. The presence of thrombocytosis and thrombocytopenia did not appear to have any influence upon their results, but they made no attempt to correct for platelet contamination.…”

“…Though smaller and accounting for a very much lower oxygen consumption per cell than the average leukocyte, platelets, because of their large number, are responsible for an oxygen consumption which is about equal to that due to leukocytes per unit volume of blood [73]. Platelets are, therefore, a serious source of ambiguity in leukocyte respiratory measurements.…”

“…The existence within all leukocytes of mitochondria, which are the intracellular loci of Krebs cycle activity in all eukaryotic cells and invariably contain the enzymes of this cycle, provide a priori evidence for the presence of the enzymes of the tricarboxylic acid cycle in these cells. Respiration may be stimulated by the metabolic inter mediates of the Krebs cycle [54,73]. In intact leukocytes, succinate, pyru vate and a-glycerophosphate are capable of this stimulation [54,73], though it has been claimed by some [54] that of these only pyruvate is fully active in intact cells, while the other two substrates are stimulatory only in modified leukocytes.…”

“…Respiration may be stimulated by the metabolic inter mediates of the Krebs cycle [54,73]. In intact leukocytes, succinate, pyru vate and a-glycerophosphate are capable of this stimulation [54,73], though it has been claimed by some [54] that of these only pyruvate is fully active in intact cells, while the other two substrates are stimulatory only in modified leukocytes. The demonstration of this latter activity by Wagner et al [73] was obtained on cell suspensions extensively dialyzed against distilled water, which could have modified their permeability characteristics.…”

“…In intact leukocytes, succinate, pyru vate and a-glycerophosphate are capable of this stimulation [54,73], though it has been claimed by some [54] that of these only pyruvate is fully active in intact cells, while the other two substrates are stimulatory only in modified leukocytes. The demonstration of this latter activity by Wagner et al [73] was obtained on cell suspensions extensively dialyzed against distilled water, which could have modified their permeability characteristics. On the other hand, Foster and Terry [37], using isolated mitochondria, pro bably derived from both granulocytes and platelets, showed that virtually all substrates of the Krebs cycle provide some stimulation of oxygen consump tion.…”