cyclic-gmp and Angina--Unstable

Therapeutic activation of the vascular NO/cGMP pathway is induced by a variety of stimuli/mediators including physical activity, supplementation with the precursor L-arginine and organic nitrates which generate NO in the vasculature. The necessity of an enzymatic reduction for NO generation from these drugs as well as differences in the activity of the NO/cGMP pathway within the vascular tree determine the unique hemodynamic changes elicited by organic nitrates. These changes include preferential venodilation, vessel-size specific arterial dilation and improvement of the aortic distensibility and Windkessel-function. Some animal experiments and clinical investigations suggest that nitrates may also be endowed with cardioprotective and/or vasoprotective effects. "Early entry" therapy with nitrates do not significantly improve survival in myocardial infarction but increases the beneficial effects of the ACE-inhibitor enalapril by 50%. Furthermore, nitrates have been shown to improve survival in heart failure, but prognostic effects in stable angina pectoris are unknown. Short-term experimental and clinical investigations suggest that nitrate tolerance induced by nitroglycerin is associated with toxic effects in the vasculature, but this is not true for pentaerythrityl tetranitrate and isosorbide mononitrate. The observed endothelial dysfunction induced by a continuous treatment with nitroglycerin may be an additional risk for patients who receive continuous nitroglycerin to treat conditions such as unstable angina and acute heart failure. In general, nitrates are remarkably safe drugs and are well tolerated. Appropriate clinical trials are needed to answer the question whether nitrates can do more than symptomatic relief in cardiovascular disease.

Topics: Angina, Unstable; Animals; Cardiovascular Diseases; Cyclic GMP; Enalapril; Endothelium, Vascular; Hemodynamics; Humans; Myocardial Infarction; Nitrates; Nitric Oxide; Nitroglycerin; Platelet Aggregation

A multi-class classification model for acute coronary syndrome (ACS) remains to be constructed based on multi-fluid metabolomics. Major confounders may exert spurious effects on the relationship between metabolism and ACS. The study aims to identify an independent biomarker panel for the multiclassification of HC, UA, and AMI by integrating serum and urinary metabolomics. We performed a liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics study on 300 serum and urine samples from 44 patients with unstable angina (UA), 77 with acute myocardial infarction (AMI), and 29 healthy controls (HC). Multinomial machine learning approaches, including multinomial adaptive least absolute shrinkage and selection operator (LASSO) regression and random forest (RF), and assessment of the confounders were applied to integrate a multi-class classification biomarker panel for HC, UA and AMI. Different metabolic landscapes were portrayed during the transition from HC to UA and then to AMI. Glycerophospholipid metabolism and arginine biosynthesis were predominant during the progression from HC to UA and then to AMI. The multiclass metabolic diagnostic model (MDM) dependent on ACS, including 2-ketobutyric acid, LysoPC(18:2(9Z,12Z)), argininosuccinic acid, and cyclic GMP, demarcated HC, UA, and AMI, providing a C-index of 0.84 (HC vs. UA), 0.98 (HC vs. AMI), and 0.89 (UA vs. AMI). The diagnostic value of MDM largely derives from the contribution of 2-ketobutyric acid, and LysoPC(18:2(9Z,12Z)) in serum. Higher 2-ketobutyric acid and cyclic GMP levels were positively correlated with ACS risk and atherosclerosis plaque burden, while LysoPC(18:2(9Z,12Z)) and argininosuccinic acid showed the reverse relationship. An independent multiclass biomarker panel for HC, UA, and AMI was constructed using the multinomial machine learning methods based on serum and urinary metabolite signatures.

Topics: Acute Coronary Syndrome; Angina, Unstable; Argininosuccinic Acid; Biomarkers; Chromatography, Liquid; Cyclic GMP; Humans; Myocardial Infarction; Tandem Mass Spectrometry

Various dosing strategies to determine therapeutic effects of nitroglycerin (NTG) preparations are reviewed. The importance of individual patient titration in establishing an effective NTG dosage is emphasized by reviewing a nitroglycerin ointment study and a crossover study. Studies reporting the development of hemodynamic attenuation ("tolerance") with longterm nitrate therapy are also discussed. The results of these and other studies suggest that the magnitude of the hemodynamic response to NTG or isosorbide dinitrate diminishes over time, with acute or first-dose effects far exceeding those obtained during long-term therapy. However, patients on long-term therapy continue to respond to sublingual NTG, which suggests that this phenomenon is not true NTG tolerance. The effect of a nitrate-free interval as a mechanism for avoiding hemodynamic attenuation of NTG therapy is reviewed. The results of 4 studies discussed found that intermittent nitrate protocols were not associated with the attenuated hemodynamic effect observed during chronic therapy. Two possible mechanisms for the vasodilatory effects of nitroglycerin are discussed. The first relates to the production of cyclic guanosine monophosphate in the smooth muscle cells of arteries and veins; the second to the synthesis of prostaglandin I2 by vascular endothelial cells. A mechanism by which nitrate receptors could be manipulated to increase vascular responsiveness is theorized, as well as a means by which a nitrate-free interval might avoid the development of hemodynamic attenuation in terms of cellular mechanisms and receptors.

Topics: Acetylcysteine; Administration, Oral; Administration, Topical; Angina Pectoris; Angina, Unstable; Animals; Blood Vessels; Cheek; Cyclic GMP; Drug Administration Schedule; Drug Tolerance; Electrocardiography; Endothelium; Exercise Test; Hemodynamics; Humans; Infusions, Parenteral; Isosorbide Dinitrate; Nitroglycerin; Prostaglandins; Vascular Resistance