(1/422) Prostaglandin endoperoxide-dependent vasospasm in bovine coronary arteries after nitration of prostacyclin synthase.
In the present study we used a bioassay to study the effects of peroxynitrite (ONOO-) on angiotensin II (A-II)-triggered tension in isolated bovine coronary arteries in order to show the consequences of the previously reported PGI2-synthase inhibition by ONOO- in this model. The following results were obtained: 1. 1 micromol L(-1) ONOO- impaired A-II-induced vasorelaxation and caused a second long lasting constriction phase. Indomethacin (10(-5)M) prevented both effects. U51605, a dual blocker of PGI2-synthase and thromboxane (TX)A2-synthase mimicked the effects of ONOO-. 2. The selective TXA2/prostaglandin endoperoxide (PGH2) receptor antagonist SQ29548 antagonized the second vasoconstriction phase after ONOO- -treatment. Since a generation of TXA2 and 8-iso-prostaglandin F2alpha could be excluded a direct action of unmetabolized PGH2 on the TXA2/PGH2 receptor was postulated. 3. ONOO- dose-dependently inhibited the conversion of 14C-PGH2 into 6-keto-PGF1alpha in isolated bovine coronary arteries with an IC50-value of 100 nM. 4. Immunoprecipitation of 3-nitrotyrosine-containing proteins with a monoclonal antibody revealed PGI2-synthase as the only nitrated protein in bovine coronary arteries treated with 1 micromol 1(-1) ONOO-. 5. Using immunohistochemistry a co-localization of PGI2-synthase and nitrotyrosine-containing proteins was clearly visible in both endothelial and vascular smooth muscle cells. We concluded that ONOO- not only eliminated the vasodilatory, growth-inhibiting, antithrombotic and antiadhesive effects of PGI2 but also allowed and promoted an action of the potent vasoconstrictor, prothrombotic agent, growth promoter, and leukocyte adherer, PGH2. (+info)
(2/422) Racial heterogeneity in coronary artery vasomotor reactivity: differences between Japanese and Caucasian patients.
Japanese investigators have provided a substantial contribution in the understanding of coronary vasomotor reactivity. On occasions, their findings have been at variance with those undertaken on caucasian patients, raising speculation that vasomotor differences between races may exist. In a comparative review of the published literature, we evaluated the vasoreactive differences among Japanese and caucasian patients with variant angina or myocardial infarction. In variant angina, Japanese patients appear to have diffusely hyperreactive coronary arteries compared with caucasian people, manifested by their segmental rather than focal spasm, hyperreactive nonspastic vessels and multivessel spasm. These differences may reflect the increased basal tone among Japanese variant angina patients and may relate to controversial differences in endothelial nitric oxide production or autonomic nervous system activity. Provocative vasomotor studies of Japanese patients with a recent myocardial infarction report a higher incidence of inducible spasm than caucasian studies, an observation recently supported by a controlled study. Furthermore, the hyperreactivity was diffuse, occurring in both non-infarct- and infarct-related vessels. These observations support the existence of racial coronary vasomotor reactivity differences but require confirmation in further prospectively conducted studies. (+info)
(3/422) Intraoperative spasm of coronary and peripheral artery--a case occurring after tourniquet deflation during sevoflurane anesthesia.
A 68-yr-old man with a 9-yr history of hypertension presented for hemiglossectomy, segmental resection of the mandible, and the radial forearm free flap grafting. Intraoperatively, facial artery spasm was observed during microvascular suturing of the radial artery to the facial artery. Simultaneously, systolic blood pressure decreased from 100 to 80 torr and the ST segment elevated to 15 mm from the base line. The possible mechanisms responsible for vasospasm in coronary as well as in peripheral arteries under sevoflurane anesthesia are discussed. (+info)
(4/422) T-786-->C mutation in the 5'-flanking region of the endothelial nitric oxide synthase gene is associated with coronary spasm.
BACKGROUND: Coronary spasm plays an important role in the pathogenesis of ischemic heart diseases in general. However, the precise mechanism(s) responsible for coronary spasm remains to be elucidated, and we examined the molecular genetics of coronary spasm. METHODS AND RESULTS: We searched for the possible mutations in the endothelial nitric oxide synthase (eNOS) gene in patients with coronary spasm. In this study, we demonstrate the existence of 3 linked mutations in the 5'-flanking region of the eNOS gene (T-786-->C, A-922-->G, and T-1468-->A). The incidence of the mutations was significantly greater in patients with coronary spasm than in the control group (P<0.0001). Multiple logistic regression analysis with forward stepwise selection using the environmental risk factors and the eNOS gene variant revealed that the most predictive independent risk factor for coronary spasm was the mutant allele (P<0.0001). As assessed by luciferase reporter gene assays, the T-786-->C mutation resulted in a significant reduction in eNOS gene promoter activity (P<0.05), whereas neither the A-922-->G nor the T-1468-->A mutation had any affect. CONCLUSIONS: Taken together, these findings strongly suggest that the T-786-->C mutation in the eNOS gene reduces the endothelial NO synthesis and predisposes the patients with the mutation to coronary spasm. (+info)
(5/422) A case of vasospastic angina presenting Brugada-type ECG abnormalities.
An electrophysiological study and a provocative test of coronary artery spasm was attempted in a 68-year-old man who was having syncopal attacks and chest pain. His electrocardiogram had the characteristics of Brugada syndrome and ventricular fibrillation (VF) was induced by programmed electrical stimulation. ST-segment elevation became exaggerated by procainamide, which could not prevent the induction of VF. Coronary angiography revealed no stenotic lesions, and spasm in the left coronary artery was induced by intracoronary administration of acetylcholine with similar chest pain to that experienced before. Under treatment with diltiazem and flecainide, which suppressed the induction of VF, the patient experienced no recurrence of symptoms despite persistent ST-segment elevation. No previous reports have described coronary spasm associated with Brugada-type ECG abnormalities, and patients with syncope should be evaluated carefully. (+info)
(6/422) Hypoxia-reoxygenation triggers coronary vasospasm in isolated bovine coronary arteries via tyrosine nitration of prostacyclin synthase.
The role of peroxynitrite in hypoxia-reoxygenation-induced coronary vasospasm was investigated in isolated bovine coronary arteries. Hypoxia-reoxygenation selectively blunted prostacyclin (PGI2)-dependent vasorelaxation and elicited a sustained vasoconstriction that was blocked by a cyclooxygenase inhibitor, indomethacin, and SQ29548, a thromboxane (Tx)A2/prostaglandin H2 receptor antagonist, but not by CGS13080, a TxA2 synthase blocker. The inactivation of PGI2 synthase, as evidenced by suppressed 6-keto-PGF1 alpha release and a decreased conversion of 14C-prostaglandin H2 into 6-keto-PGF1 alpha, was paralleled by an increased nitration in both vascular endothelium and smooth muscle of hypoxia-reoxygenation-exposed vessels. The administration of the nitric oxide (NO) synthase inhibitors as well as polyethylene-glycolated superoxide dismutase abolished the vasospasm by preventing the inactivation and nitration of PGI2 synthase, suggesting that peroxynitrite was implicated. Moreover, concomitant administration to the organ baths of the two precursors of peroxynitrite, superoxide, and NO mimicked the effects of hypoxia-reoxygenation, although none of them were effective when given separately. We conclude that hypoxia-reoxygenation elicits the formation of superoxide, which causes loss of the vasodilatory action of NO and at the same time yields peroxynitrite. Subsequently, peroxynitrite nitrates and inactivates PGI2 synthase, leaving unmetabolized prostaglandin H2, which causes vasospasm, platelet aggregation, and thrombus formation via the TxA2/prostaglandin H2 receptor. (+info)
(7/422) Transient severe mitral regurgitation complicating myocardial stunning due to coronary vasospasm.
As in papillary muscle dysfunction complicating mitral prolapse, dyskinesis of the left ventricular wall underlying the papillary muscles has been shown to cause mitral regurgitation following myocardial infarction. Myocardial stunning has been experimentally evidenced to cause mitral regurgitation due to a wall motion abnormality, but it has not yet been clinically defined. We report a clinical case of transient severe mitral regurgitation complicating myocardial stunning caused by coronary vasospasm. Transient wall motion abnormality beneath the anterolateral papillary muscle was considered to be responsible for the mitral regurgitation. (+info)
(8/422) Prognostic significance of the pattern of multivessel spasm in patients with variant angina.
Multivessel spasm in variant angina is believed to be a major prognostic factor. Three patterns of multivessel spasm have been detected: (1) spasm at different sites on different occasions (migratory spasm); (2) spasm sequentially affecting 2 different sites (sequential spasm); and (3) simultaneous spasm at more than 1 site (simultaneous spasm). The present study investigated the prognosis based on this factor for variant angina without fixed coronary stenosis and examined the influence of multivessel spasm on cardiac events. Twenty-six patients were diagnosed as having variant angina without fixed coronary stenosis using 12-lead 24-h ECG recording system and coronary cineangiography. These patients were followed up prospectively for 57.1+/-7.6 months. Of the 26 patients 13 had single-vessel spasm, 6 had migratory multivessel spasm angina, and 7 showed sequential and/or simultaneous multivessel spasm angina. The survival free of serious cardiac events and of all cardiac events was significantly lower for patients with sequential and/or simultaneous multivessel spasm than for those with migratory multivessel spasm (p<0.05, p<0.05), whereas for patients with migratory multivessel spasm the difference comparison with single-vessel spasm did not attain statistical significance (p = ns, p = ns). The results of this study suggest that there seems to be a high-risk subgroup (i.e., sequential and/or simultaneous multivessel spasm) among patients with variant angina. (+info)