We have investigated the contribution of Ca2+/calmodulin-dependent protein 
kinase II (CaM kinase II) and mitogen-activated protein kinase (MAP kinase) in 
norepinephrine (NE)-induced arachidonic acid (AA) release in rabbit aortic 
vascular smooth muscle cells (VSMC). NE enhanced release of AA via activation of 
cytosolic phospholipase A2 (cPLA2) but not secretory PLA2 in VSMC prelabeled 
with [3H]AA. NE (10 microM) enhanced CaM kinase II and MAP kinase activity. In 
cells transiently transfected with antisense oligonucleotides complementary to 
the translation initiation sites of CaM kinase II and MAP kinase, NE-induced AA 
release was inhibited by 100 and 35% respectively. Treatment of cells with 
PD-098059, a MAP kinase kinase inhibitor, or with MAP kinase antisense 
oligonucleotide reduced NE-induced activation of MAP kinase and cPLA2. 
NE-induced MAP kinase and cPLA2 activation was also inhibited in cells treated 
with a CaM kinase II inhibitor, KN-93, or with CaM kinase II antisense 
oligonucleotide. On the other hand, inhibition of MAP kinase kinase with 
PD-098059 or of MAP kinase with antisense oligonucleotides did not alter the 
NE-induced increase in CaM kinase II activity. Phosphorylation of MAP kinase and 
CaM kinase II by NE, studied by 32P incorporation and immune complex kinase 
assays, was inhibited by KN-93. Collectively, these data suggest that CaM kinase 
II can activate MAP kinase, which in turn activates cPLA2 to release AA for 
prostacyclin synthesis in the rabbit VSMC. This novel pathway for activation of 
MAP kinase by CaM kinase II appears to be mediated through stimulation of MAP 
kinase kinase. Activation of adrenergic receptors with NE in VSMC caused 
translocation of CaM kinase II, MAP kinase, and cPLA2 to the nuclear envelope 
only in the presence of extracellular Ca2+. Okadaic acid, which increased 
phosphorylation and activity, did not translocate these enzymes. Therefore, it 
appears that in rabbit VSMC, NE, by promoting extracellular Ca2+ influx, 
increases CaM kinase II activity, leading to activation of MAP kinase and cPLA2 
and translocation to the nuclear envelope, resulting in release of AA from the 
nuclear envelope for prostacyclin synthesis.