Association of the phosphatidylinositol signal pathway with prolonged myocardial ischemia.
OBJECTIVE: To study the changes in activity of phosphatidylinositol 4 kinase (PI 4 kinase), phosphatidylinositol 4 phosphate 5 kinase (PIP 5 kinase) and protein kinase C (PKC) during myocardial ischemia and elucidate the relationship between phosphatidylinositol signal pathways and prolonged myocardial ischemia. METHODS: In vivo an ischemic rat model was used. Activity of PI 4 kinase, PIP 5 kinase and PKC were measured at different times in postischemic heart cells using isotope analysis. RESULTS: The activity of PI kinase, PIP kinase and PKC in the myocardium increased to peak at 1 hour postischemia, with activities 6.1, 3.0 and 4.0 fold over control levels, respectively. Their activities declined to normal levels with time. CONCLUSION: The phosphatidylinositol signal pathway is involved in prolonged myocardial ischemia, but its mechanism needs further study.