Serotonin-induced human coronary microvascular contraction during acute myocardial ischemia is blocked by COX-2 inhibition.
Since serotonin (5-HT) is implicated in exacerbating acute coronary syndromes, we studied the reactivity of atrial coronary arterioles (70-140 microm) of atherosclerotic patients undergoing cardiac surgery to 5-HT, substance P (Sub P), and sodium nitroprusside by video-microscopy. Before ischemia, 5-HT-induced relaxation was not affected by NS398 (cyclooxygenase inhibitor), H2O2 or U63557A (thromboxane A2 synthase inhibitor), but was reduced by L-NNA. 5-HT elicited a potent contractile response after ischemia that was inhibited by NS398, Indo, and U63557A. While Sub P relaxation was decreased after ischemia, SNP relaxation was unchanged. The mRNA steady-state levels of NOS-3, NOS-2, prostacyclin synthase, and COX- 1 were not altered by ischemia. COX-2 mRNA and protein levels (Westernblotting), however, were increased (mean +/- SEM) 2.4 +/- 0.4 and 3.2 +/- 0.7 fold, respectively, in ischemic atrium corroborating with the immunohistochemistry of atrial tissue. It is concluded that myocardial ischemia enhanced contractile response of coronary arterioles to 5-HT maybe due to the stimulated prostaglandin release (likely thromboxane A2) secondary to induction of COX-2 expression. These findings may have implications regarding the cause of coronary spasm during acute myocardial ischemia.
Métais
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Beth Israel Deaconess Medical Center, Division of Cardiothoracic Surgery, Boston MA 02215, USA.
Bianchi
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Li
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Li
J
J
Simons
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M
Sellke
F W
FW
D000368:Aged; D003331:Coronary Vessels / Q000187:drug effects* / Q000503:physiopathology*; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D005260:Female; D006325:Heart Atria; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins; D008833:Microcirculation / Q000187:drug effects; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000503:physiopathology*; D009206:Myocardium / Q000201:enzymology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D009599:Nitroprusside / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D012701:Serotonin / Q000494:pharmacology*; D013373:Substance P / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects*
D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D009599:Nitroprusside; D012701:Serotonin; D013373:Substance P; C496319:NOS2 protein, human; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases