Alteration of human platelet protein kinase C with normal aging

Using a two-site enzyme immunoassay, we determined the content of type II protein kinase C (PKC) in human platelets from 24 donors of various ages without any neurological, hematological or malignant disorders. The content of type II PKC in the membranous fraction was positively correlated with aging. The content of PKC in the cytosolic fraction tended to decline with aging, but the correlation was not significant. The total amount of PKC also had no significant correlation with aging. Age-related changes in platelet protein content were not observed. These results suggested that the subcellular distribution of type II PKC in human platelets is altered with normal aging.