A step in the process of prostacyclin production whose decline leads to the age-related decrease in production by human umbilical vein endothelial cells in culture.

Human umbilical vein endothelial (HUVE) cells were examined at various culture ages for four steps of prostacyclin (PGI2) production ((1) incorporation of exogenous arachidonic acid into the cell membrane, (2) loss of arachidonic acid from the cell membrane to the cytoplasm, (3) conversion of arachidonic acid to PGI2 in the cytoplasm, (4) release of PGI2 to the outside of the cell) to determine the step whose decline leads to the age-related decrease in PGI2 production. Only conversion to PGI2 (step 3) showed the age-related decrease. Judging from these results, the authors conclude that the age-related decrease in PGI2 production is mainly due to the decrease in the ability of HUVE cells to convert arachidonic acid to PGI2 in the cytoplasm.