Lysophosphatidylcholine potentiates the mitogenic effect of various vasoactive compounds on rabbit aortic smooth muscle cells.
We examined the mechanism of action of lysophosphatidylcholine (lyso-PC), which is suggested to be involved in the pathogenesis of atherosclerosis and inflamatory disorders, and its interaction with well-known vasoactive compounds such as hydrogen peroxide (H2O2), thromboxane A2 (TX-A2), serotonin (5-HT), angiotensin II (Ang-II), endothelin-1 (ET-1), or urotensin II (U-II) on VSMC proliferation. Growth-arrested rabbit VSMCs were incubated with given concentrations of lyso-PC with H202, TX-A2, 5-HT, Ang-II, ET-1, or U-II. [3H]Thymidine incorporation into DNA was measured as an index of VSMC proliferation. Lyso-PC induced a maximal effect on [3H]thymidine incorporation at a concentration of 15 microM (156%), and its effect was significantly inhibited by the phospholipase C inhibitor U73122 (10 microM), the intracellular antioxidant NAC (400 microM), and the NADPH oxidase inhibitor diphenylene iodonium (1 microM), but not by the MAPK kinase inhibitor (10 microM). H2O2, TX-A2, 5-HT, Ang-II, ET-1, or U-II also stimulated [3H]thymidine incorporation in a dose-dependent manner. A non-mitogenic concentration of lyso-PC (5 microM) significantly potentiated the effect of low concentrations of H2O2 (0.1 microM, 110 to 222%), TX-A2 (5 microM, 120 to 202%), 5-HT (5 microM, 182 to 259%), Ang-II (0.5 microM, 167 to 304%), ET-1 (0.01 microM, 139 to 297%), or U-II (0.025 microM, 120 to 332%) on [3H]thymidine incorporation. The results suggest that lyso-PC acts synergistically with the vasoactive compounds H2O2, TX-A2, 5-HT, Ang-II, ET-1, or U-II in inducing VSMC proliferation, which may play an important role in the progression of atherosclerosis.
Watanabe
Takuya
T
Third Department of Internal Medicine, Showa University School of Medicine, Tokyo, Japan.
Koba
Shinji
S
Katagiri
Takashi
T
Pakala
Rajbabu
R
Benedict
Claude R
CR
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000166:cytology*; D001161:Arteriosclerosis / Q000473:pathology; D002478:Cells, Cultured; D004247:DNA / Q000032:analysis; D004357:Drug Synergism; D019332:Endothelin-1 / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008244:Lysophosphatidylcholines / Q000494:pharmacology*; D008934:Mitogens / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D011817:Rabbits; D012701:Serotonin / Q000494:pharmacology; D013928:Thromboxane A2 / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors; D014579:Urotensins / Q000494:pharmacology; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D019332:Endothelin-1; D008244:Lysophosphatidylcholines; D008934:Mitogens; D014579:Urotensins; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D012701:Serotonin; D013928:Thromboxane A2; D004247:DNA; C029677:urotensin II; D006861:Hydrogen Peroxide; D010738:Type C Phospholipases; D013936:Thymidine