ARACHIDONIC-ACID STIMULATES PROTEIN-KINASE C-EPSILON REDISTRIBUTION IN HEART-CELLS

Arachidonic acid is elevated in a variety of cell types in response to extracellular stimuli, and has been hypothesized to exert at least so me of its intracellular actions via activation of protein kinase C. He re we show that arachidonic acid stimulates a unique pattern of transl ocation of the epsilon-isoform of protein kinase C in isolated adult r at cardiac myocytes. Using western blot analysis, the majority of epsi lon-protein kinase C was found in a cytosolic fraction in unstimulated cells, Treatment with 50 mu M arachidonic acid caused a transient inc rease of epsilon-protein kinase C in a membrane fraction within 1 minu te, then after 5-20 minutes most was found in a filament/nuclear fract ion. Immunofluorescence and confocal microscopy of the filament fracti on revealed a striated staining pattern with epsilon-protein kinase C localized near the Z-line where actin filaments are anchored and where transverse tubules are closely apposed to the myofilaments, delta-Pro tein kinase C, another isoform highly expressed in these cells, did no t redistribute significantly in response to arachidonic acid.