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Research Article Free access | 10.1172/JCI105542
Department of Medicine, New York University Medical Center, New York, N. Y.
†Career Scientist, New York Health Research Council.
Address requests for reprints to Dr. Simon Karpatkin, Dept. of Medicine, New York University Medical Center, 550 1st Ave., New York, N. Y. 10016.
*Submitted for publication July 27, 1966; accepted November 23, 1966.
Supported by New York Health Research Council grant U-1529.
Presented at the Ninth Meeting of the American Society of Hematology, December 4, 1966, New Orleans, La.
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Published March 1, 1967 - More info
Evidence for a metabolically active plasma-free platelet system is presented. Glycogenolysis was found to be a potent pathway for lactate production. Aerobic glycolysis constituted a major fraction of glucose metabolized. Both insulin and cyanide increased lactate production in the presence of glucose. The Krebs cycle appeared to be operative for ATP synthesis when citrate was used as substrate. The first stages of gluconeogenesis were noted to be present. Glucose uptake contributed to increased lactate production.
Thrombin, epinephrine, and ADP resulted in platelet agglutination and contraction and increased platelet glycogenolysis (phosphorylase activity). Epinephrine appeared to be a more potent activator of phosphorylase, resulting in a 70% increase in glucose 6-phosphate levels. Thrombin and epinephrine both increased glucose uptake and lactate production. Glucose uptake decreased in the presence of ADP. Except for incubations with epinephrine, glucose 6-phosphate remained constant under conditions in which lactate flux increased 3-fold and glucose uptake increased 2-fold. Thrombin, epinephrine, and ADP decreased ATP levels in the presence or absence of glucose.