1. Analysis of Lysophophatidylcholine-Induced Endothelial Dysfunction
- Author
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W. Y. Kuo, Michael A. Levine, B. Drenger, Nicholas A. Flavahan, J. E. Freeman, and T. N. Barnett
- Subjects
medicine.medical_specialty ,Endothelium ,Arteriosclerosis ,Swine ,Blotting, Western ,Bradykinin ,Stimulation ,GTP-Binding Protein alpha Subunits, Gi-Go ,Biology ,Dinoprost ,Nitric Oxide ,Pertussis toxin ,Muscle, Smooth, Vascular ,Nitric oxide ,chemistry.chemical_compound ,Superoxides ,Internal medicine ,medicine ,Animals ,Virulence Factors, Bordetella ,Endothelial dysfunction ,Pharmacology ,Lysophosphatidylcholines ,medicine.disease ,Vasodilation ,Lysophosphatidylcholine ,Endocrinology ,medicine.anatomical_structure ,Pertussis Toxin ,chemistry ,Mastoparan ,Endothelium, Vascular ,Cardiology and Cardiovascular Medicine - Abstract
Endothelial dysfunction caused by the early atherosclerotic process or by endothelial exposure to atherogenic lipids, including lysophosphatidylcholine (lysoPC), is characterized by a selective impairment of responses mediated by the pertussis toxin-sensitive Gi-2 protein. Experiments were performed to analyze the mechanisms underlying this effect. Bradykinin (BK: Gi-2 protein-independent), serotonin (5-HT: Gi-2 protein-dependent), or direct activation of the G(i-2)-protein by mastoparan increased the release of endothelium-derived nitric oxide (EDNO) from porcine arterial endothelial cells (EC). LysoPC decreased the release of EDNO caused by 5-HT, but did not affect the response to BK or mastoparan. LysoPC did not increase production of superoxide radicals detected by lucigenin-enhanced chemiluminescence. Western blot analysis showed no difference in the level of immunoreactive Gi alpha-2 between control and lysoPC-treated cells. Activation of the Gi-2 protein by serotonergic or alpha 2-adrenoceptor stimulation decreased the pertussis toxin-catalyzed ADP-ribosylation of Gi alpha-2 protein in membranes from control but not lysoPC-treated cells. However, direct activation of the Gi-2 protein by mastoparan inhibited the ADP-ribosylation in membranes from control and lysoPC-treated cells. The toxin-catalyzed reaction was reduced in lysoPC-treated cells or lysoPC-treated membranes. LysoPC reduced the ability of endothelin to increase GTP gamma S binding to the Gi-2 protein but did not affect the activity of mastoparan. These results suggest that lysoPC inhibits a pertussis toxin-sensitive signaling pathway in EC by an effect consistent with receptor:Gi-2-protein uncoupling.
- Published
- 1996
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