Heterogeneity of human platelets

Abstract

A B S T R A C T Human platelets were separated by density-centrifugation into heavy and light populations. Heavy platelets have an average volume approximately twofold greater than light platelets, and have previously been shown to be young platelets.All 11 enzymes of the Embden-Meyerhof pathway plus the five related enzymes: phosphoglucomutase, glucose-6-P dehydrogenase, 6-P-gluconic dehydrogenase, a-glycerol-P dehydrogenase, and glutathione reductase (TPNH) were examined in cell lysates from total, heavy, and light platelet populations. Apparent Km for individual enzymes were measured in a total platelet population. Empirical Vm.. of the individual enzymes were measured in total, heavy, and light platelet populations. The three apparent rate-limiting enzymes for glycolysis were hexokinase, phosphofructokinase, and glyceraldehyde-3-P dehydrogenase.Heavy platelets contained approximately twofold greater enzyme activity (per gram wet weight) than light platelets for 7 of the 16 enzymes measured: hexokinase, phosphohexoisomerase, phosphofructokinase, glyceraldehyde-3-P dehydrogenase, phosphoglycerokinase, lactic dehydrogenase, and phosphoglucomutase.

Platelet storage at 22°C; metabolic, morphologic, and functional studies

“…These values are essentially identical with those reported by Karpatkin (18) but one-half to two-thirds of those reported by others (19,20 (Fig. 3) while the small amount of glucose-'C converted to C02 increased exponentially.…”

Trauma and Acetylsalicylic Acid-Induced Changes in Hemostasis during Liver Resection in the Rat

“…It is possible that the platelets entering the circulation from blood de pots to compensate for the aggregated and destroyed ones were not as active hemostatically. It has been shown that in normal subjects circulating platelets display heterogeneity o f size, density and metabolic function with larger ones showing greater metabolic activity (14,19). Weston et al (45) have shown that, after charcoal hemoperfusion in patients with fulminant hepatic failure, mean median volume o f platelets decreased and capillary bleeding time was doubled despite the limited drop in arterial platelet counts.…”

Platelet function in fulminant hepatic failure and effect of charcoal haemoperfusion.

“…Indeed, the five patients with capillary bleeding times over 30 minutes but platelet counts above 100 x 109/1 would seem to have a considerable degree of platelet dysfunction. In normal subjects circulating platelets display heterogeneity of size, density, and metabolic function with the larger ones i-L. showing greater metabolic activity (Karpatkin and Charmatz,, 1969;Ginsburg and Aster, 1972). If these larger platelets are haemostatically the most active, then their selective deficiency in fulminant hepatic failure could explain the low platelet volumes found and the long capillary bleeding times.…”