Accession Number : ADA955167

Title :   Human Platelet Senescence.

Descriptive Note : Annual summary rept. no. 3, 1 Jul 70-30 Jun 71,

Corporate Author : NEW YORK UNIV MEDICAL CENTER N Y

Personal Author(s) : Karpatkin,Simon

Report Date : 30 JUN 1971

Pagination or Media Count : 4

Abstract : Recent work has been directed towards an attempt to determine the critical rate-limiting steps controlling in vitro platelet senescence. Large-heavy platelets (megathrombocytes) were incubated sterilely in their own plasma for 17 hours and the enzymes of the Embden-Meyerhof pathway (ATP generation) and related oxidative-reductive enzymes examined. The half-life of enzyme activity was compared with the differences noted between heavy and light platelet populations (younger and older platelets) at initial extraction. The more labile enzymes, noted during sterile incubation of large-heavy platelets (megathrombocytes) proved to be the (very same) enzymes which were present at approximately two fold the concentration in heavy platelets compared to light platelets during initial extraction. Furthermore, these labile enzymes included the 3 rate-limiting enzymes of the Embden-Meyerhof pathway: hexokinase, phosphofructokinase and glyceraldehyde-3-P-dehydrogenase. It was concluded, that at least with in vitro platelet senescence, heavy-large platelets might become older light-small platelets through the loss of rate-limiting enzymes which control the generation of ATP and platelet viability (maintenance of ionic gradients, discoid shape, etc.). These experiments were then taken one step further in order to determine what factors controlled the lability of the rate-limiting enzymes during in vitro senescence. A second prong of the attack on unravelling the problems of human platelet senescence and platelet heterogeneity has been directed towards the kinetics of megathrombocyte (large young platelet) production.

Descriptors :   AGING(PHYSIOLOGY), BLOOD PLATELETS, ENZYMES, HETEROGENEITY, HEXOKINASE, HUMANS, IN VITRO ANALYSIS, INCUBATION, LIGHT, POPULATION, PRODUCTION, STERILIZATION, VIABILITY

Subject Categories : Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE