AGE-RELATED AND TRAINING-RELATED EVENTS IN ACTIVE T-SUBPOPULATION - CHANGES IN POLYPHOSPHOINOSITIDE METABOLISM DURING MITOGENIC STIMULATION

To examine the effects of age and training an the active T subpopulati on we considered elderly amateur cyclists over 65 in comparison with y oung amateur cyclists and young and aged sedentary healthy controls. S ignificant differences were observed between trained and sedentary eld erly subjects consisting of an increase in the percentage of active E rosettes after 4 and 24 h of in vitro PHA stimulation, and of a decrea se in the in vitro phosphorylation of phosphatydylinositol 4,5-bisphos phate (PtdInsP(2)) and a corresponding increase in phosphatydylinosito l 4-phosphate (PtdInsP) in the early steps of the mitotic response. Ou r findings support the hypothesis of the involvement of inositol lipid s in controlling the expression of lymphocyte surface receptors.