The stimulation by thrombin of glucose oxidation in human platelets.

Abstract

Glucose oxidation by human platelets incubated in Krebs-Ringer bicarbonate buffer was measured by collection of C14O2 from glucose-1-C14 or glucose-6-C14. Platelets oxidized glucose both by the Embden-Meyerhof pathway and by the hexose monophosphate pathway. Thrombin caused platelets to increase the oxidation of glucose-1-C14 and of glucose-6-C14 in equal amounts. This was interpreted as a stimulation of the Embden-Meyerhof pathway of glucose oxidation. In contrast to the prolonged stimulation of glucose oxidation by thrombin, the stimulation of lactate production was only short-lived. Thrombin caused platelets to increase the oxidation of mannose-1-C14 and fructose-U-C14 but to decrease the oxidation of pyruvate-C14. These findings suggested that thrombin acts at a step earlier in the metabolic sequence of glucose oxidation than the entry of pyruvate. In platelets pretreated with EDTA, thrombin stimulated the hexose monophosphate pathway rather than the Embden-Meyerhof pathway. EDTA added after thrombin enhanced the stimulation of the Embden-Meyerhof pathway by thrombin. Protein synthesis was demonstrated in platelets. Inhibition of this synthesis by puromycin did not eliminate the ability of thrombin to stimulate glucose oxidation.