Thrombin stimulation of platelet oxygen consumption rate

Abstract

Oxygen consumption of human platelets was measured by O2 cathode. Platelets were prepared by collecting blood into ACD solution, and isolation and washing in buffer by centrifugation. O2 consumption was measured by vibrating cathode at 25 C in Hank's solution. The Qo2 was 14.5 ± 4.8 mμmoles/min 109 platelets with added glucose and 21.4 ± 5.0 with added glycerol. Thrombin addition resulted in increase in Qo2 of elevenfold lasting 3–5 min followed by clumping of the platelets. EDTA blocked the thrombin effect. Similar effects were noted when prothrombin was activated to form thrombin. 5-Hydroxytryptamine was without effect. With EDTA the reaction had two phases, a phase of thrombin effect and a calcium-dependent clumping phase. The observations are compatible with the hypothesis that thrombin alters platelet permeability. platelet clumping; viscous metamorphosis of platelets; platelet respiration measurement by O2 cathode; thrombin effect on platelet respiration; platelet respiration; platelet intermediary metabolism Submitted on September 20, 1963