Modulation of constitutive nitric oxide synthase, bcl-2 and Fas expression in cultured human coronary endothelial cells exposed to anoxia-reoxygenation and angiotensin II: role of AT1 receptor activation.
BACKGROUND
Angiotensin II (Ang II) plays a critical role in the pathophysiology of myocardial ischemia-reperfusion injury. We have recently shown that reoxygenation following a period of anoxia causes apoptosis of cultured human coronary artery endothelial cells (HCAECs). Ang II further enhances apoptosis of HCAECs via Ang II type 1 receptor (AT1R) activation. Recent studies suggest an important role of constitutive nitric oxide synthase (cNOS), Fas and bcl-2 proteins in apoptosis. This study was designed to examine the modulation of cNOS, and Fas and bcl-2 expression in HCAECs during exposure to anoxia-reoxygenation and Ang II.


RESULTS
HCAECs were exposed to anoxia-reoxygenation and Ang II. Anoxia-reoxygenation significantly decreased cNOS mRNA, protein and activity in cultured HCAECs (P < 0.05 vs. control). Anoxia-reoxygenation also caused an increase in Fas and a decrease in bcl-2 protein expression in cultured HCAECs (both P < 0.05 vs. control). The presence of Ang II (0.3 microM) further enhanced these effects of anoxia-reoxygenation on cNOS, Fas and bcl-2 expression. The effects of Ang II were significantly attenuated by the AT1R inhibitor losartan (10 microM).


CONCLUSIONS
During exposure of HCAECs to anoxia-reoxygenation and Ang II, AT1R activation induces important changes in cNOS mRNA, protein expression and activity, as well as bcl-2 and Fas protein expression which may have a bearing on the development of apoptosis.
D000704:Analysis of Variance; D000804:Angiotensin II / Q000494:pharmacology*; D000959:Antihypertensive Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D003331:Coronary Vessels; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D019808:Losartan / Q000494:pharmacology; D015428:Myocardial Reperfusion Injury / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011945:Receptors, Angiotensin / Q000187:drug effects; D019014:fas Receptor / Q000378:metabolism*