Norepinephrine-Induced Stimulation of p38 Mitogen-Activated Protein Kinase Is Mediated by Arachidonic Acid Metabolites Generated by Activation of Cytosolic Phospholipase A₂ in Vascular Smooth Muscle Cells

Abstract

p38 mitogen-activated protein kinase (MAPK) is activated by norepinephrine (NE) in the vasculature and is implicated in vascular smooth muscle hypertrophy, contraction, and cell migration. NE promotes influx of Ca 2ϩ and activates cytosolic phospholipase A 2 (cPLA 2 ) in vascular smooth muscle cells (VSMC). The purpose of this study was to determine the contribution of cPLA 2 -generated arachidonic acid (AA) and its metabolites to the activation of p38 MAPK measured by its phosphorylation, in response to NE in rabbit VSMC. NE-induced p38 MAPK activation was found to be mediated through the stimulation of ␣-1 and ␣-2 adrenergic receptors, was dependent on extracellular Ca 2ϩ , and was attenuated by an inhibitor of cPLA 2 (pyrrolidine-1). Moreover, the cPLA 2 product, AA, activated p38 MAPK in VSMC. p38 MAPK activation elicited by NE was decreased significantly by the lipoxygenase (LO) inhibitor baicalein, and to a lesser extent by the cytochrome P450 inhibitor 17-octadecynoic acid, but was not affected by the cyclooxygenase inhibitor indomethacin. The LO metabolites of AA, namely 5(S)-hydroxyeicosatetraenoic acid (HETE), 12(S)-HETE, and 15(S)-HETE and the cytochrome P450 metabolite 20-HETE, activated p38 MAPK. NE-induced p38 MAPK stimulation was found to be independent of phospholipase D (PLD) activation in rabbit VSMC. Transactivation of the epidermal growth factor receptor (EGFR) by NE also did not contribute to p38 MAPK activation. These data suggest that cPLA 2 -generated AA and its LO metabolites mediate NE-induced p38 MAPK stimulation in rabbit VSMC by a mechanism that is independent of PLD and EGFR activation.

Hypoxia Enhances Lysophosphatidic Acid Responsiveness in Ovarian Cancer Cells and Lysophosphatidic Acid Induces Ovarian Tumor Metastasis In vivo

“…cPLA 2 activation and its involvement in cell migration have previously been reported almost exclusively in the immune system and noncancerous cell types involved in inflammation, including hematopoeitical cells (42), endothelial cells (43,44), fibroblasts (45), and smooth muscle cells (46,47). We have first reported that cPLA 2 activity is required for LPA-induced cell migration in ovarian cancer cells, which is an essential component of cell invasion and tumor metastasis (14,25).…”

Involvement of p38-mitogen-activated protein kinase in adenosine receptor-mediated relaxation of coronary artery

“…For instance, p38 MAPK has been found to mediate norepinephrine (NE)-and angiotensin II-induced vasoconstriction through the phosphorylation of its substrate, heat shock protein-27 (18,27,49). Recently, it was also suggested that the cytosolic PLA 2 -generated arachidonic acid and its lipoxygenase metabolites mediate NE-induced p38 MAPK stimulation (19). p38 MAPK activation also partly contributes to impairment of N-methyl-D-aspartate-induced cerebrovasoconstriction after brain injury (3).…”

“…There are three well-characterized MAPKs: extracellular signal-regulated kinases (ERKs, or p42/44), p38, and c-Jun NH 2 -terminal kinase (JNK). These MAPKs have been linked to ischemic preconditioning, smooth muscle cell growth, vascular smooth muscle migration, and vascular contraction (16,19,45). Adenosine is reported to stimulate all MAPKs in perfused rat hearts (16).…”

“…These MAPKs have been linked to ischemic preconditioning, smooth muscle cell growth, vascular smooth muscle migration, and vascular contraction (16,19,45). Adenosine is reported to stimulate all MAPKs in perfused rat hearts (16).…”

High dietary salt reduces the contribution of 20-HETE to arteriolar oxygen responsiveness in skeletal muscle

“…Previous studies suggest that ANG II and norepinephrine (NE) may elicit vasoconstriction, in part, through 20-HETE production (1,20,24). Therefore, we also assessed arteriolar responsiveness to ANG II (1 ϫ 10 Ϫ9 M and 1 ϫ 10 Ϫ8 M, Sigma) and NE (1 ϫ 10 Ϫ7 M and 1 ϫ 10 Ϫ8 M, Sigma) before and after inhibition of 20-HETE formation with DDMS.…”