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Query: UMLS:C0002962 (angina)
 21,142 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The calcium channel-blocking activity and associated cardiovascular effects of diproteverine, a novel compound derived from papaverine, were investigated. Electrophysiological measurements in sheep Purkinje fibres showed diproteverine to reduce the amplitude of the slow action potential (IC30 = 2 microM) and to shorten the duration of the fast action potential at 50% repolarisation (IC30 = 2.5 microM). Higher concentrations (4-5 times) were required to block block the sodium channel, as assessed by a reduction in Vmax of the fast action potential. Papaverine was found to possess marginal membrane channel-blocking activity and to be much more potent than diproteverine as a cAMP-phosphodiesterase inhibitor. The most significant haemodynamic property of diproteverine, seen in anaesthetised dogs and conscious dogs pretreated with atropine, was to cause a reduction in heart rate. This appeared to be a particular feature of diproteverine as the other calcium antagonists studied produced either a smaller decrease in heart rate or tachycardia as a reflex response to hypotension. In a chronic myocardial infarct model in dogs, diproteverine caused a redistribution of the available coronary blood flow, to the benefit of an ischaemic area of the myocardium. Diproteverine resembled diltiazem in its effects on coronary blood flow, with both these agents being preferable to nifedipine and verapamil, which caused coronary steal in this model. The combination of the reduction in heart rate, to lower cardiac oxygen demand, with the beneficial action on coronary blood flow should result in diproteverine being particularly beneficial for the treatment of angina pectoris.
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PMID:Diproteverine (BRL 40015): a new type of calcium antagonist with potential antianginal properties. 205 33

The chemistry, pharmacology, pharmacokinetics, clinical uses, and adverse effects of nicardipine, nitrendipine, and bepridil are reviewed. Nicardipine, nitrendipine, and bepridil are calcium antagonists under investigation for the treatment of cardiovascular disorders. Nicardipine and nitrendipine share a common dihydropyridine nucleus with the calcium antagonist nifedipine; bepridil is unrelated to other known calcium antagonists. Like nifedipine, nicardipine and nitrendipine produce peripheral vasodilation as their predominant in vivo effect. Bepridil has vascular, sinoatrial and atrioventricular nodal, and myocardial effects qualitatively similar to those of the calcium antagonist verapamil; it also interferes with the fast sodium channel and prolongs refractoriness in atrial and ventricular tissue. Nicardipine and nitrendipine undergo extensive first-pass hepatic extraction after oral administration; oral bioavailability of bepridil is about 60%. All three drugs are highly protein bound and have been reported to increase plasma digoxin concentrations. Both nicardipine and nitrendipine are effective antihypertensive agents used alone or combined with diuretics, beta blockers, or angiotensin-converting enzyme inhibitors. Nicardipine and bepridil effectively control angina, and preliminary studies indicate that nitrendipine has antianginal properties. Bepridil may be useful in the treatment of various cardiac arrhythmias; however, its tendency to cause or worsen cardiac arrhythmias and its association with torsade de pointes may limit its usefulness. Nicardipine and nitrendipine have similar adverse effect profiles, with vasodilation-related complaints being most common. Since nicardipine, nitrendipine, and nifedipine are similar in efficacy and safety, the eventual availability of sustained-release dosage forms may determine how these drugs are ultimately used. Bepridil is an effective antianginal drug, but, because of its proarrhythmic potential, it should probably not be used as a first-line agent.
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PMID:Nicardipine, nitrendipine, and bepridil: new calcium antagonists for cardiovascular disorders. 328 Feb 22

Cardiac afferents are sensory neurons that mediate angina, pain that occurs when the heart receives insufficient blood supply for its metabolic demand (ischemia). These neurons display enormous acid-evoked depolarizing currents, and they fire action potentials in response to extracellular acidification that accompanies myocardial ischemia. Here we show that acid-sensing ion channel 3 (ASIC3), but no other known acid-sensing ion channel, reproduces the functional features of the channel that underlies the large acid-evoked current in cardiac afferents. ASIC3 and the native channel are both especially sensitive to pH, interact similarly with Ca(2+), and gate rapidly between closed, open, and desensitized states. Particularly important is the ability of ASIC3 and the native channel to open at pH 7, a value reached in the first few minutes of a heart attack. The steep activation curve suggests that the channel opens when four protons bind. We propose that ASIC3, a member of the degenerin channel (of Caenorhabditis elegans)/epithelial sodium channel family of ion channels, is the sensor of myocardial acidity that triggers cardiac pain, and that it might be a useful pharmaceutical target for treating angina.
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PMID:Acid-sensing ion channel 3 matches the acid-gated current in cardiac ischemia-sensing neurons. 1120 43

As the US population ages, the pool of patients with coronary artery disease and stable angina is projected to grow. Conventional approaches with mechanical and pharmacological therapies have made inroads toward curbing this trend, reducing the risk of future myocardial infarction and cardiac death. However, the potential benefits of currently available antianginal medications are limited by reduced work capacity, orthostasis, and important drug-drug interactions. A new approach is represented by the piperazine derivatives trimetazidine (TMZ) and ranolazine (RNZ). TMZ acts to partially inhibit fatty acid oxidation, thus shifting myocardial energy metabolism to a lower oxygen-consuming state. A total of 16 randomized trials have been completed with TMZ. In the US market, 6 trials have been completed with RNZ. RNZ has been separately classified as a late sodium channel inhibitor, which reverses action potential prolongation, suppresses early after-depolarizations, and terminates resultant ventricular tachycardia. Though it has some of the same fatty acid oxidation properties as TMZ, this is not considered its primary mechanism of action. This paper reviews medical approaches to chronic stable angina and highlights RNZ as an important advance for patients and clinicians in the US market.
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PMID:Chronic angina: new medical options for treatment. 1619 88

Chronic stable angina is common and is a difficult-to-manage problem when patients begin to fail conventional therapy especially when maximal revascularization has been provided. The most promising agent in development is ranolazine, a late sodium channel inhibitor and partial fatty oxidation inhibitor which has unique and desirable anti-ischemic and electrophysiologic properties. This agent is likely to become standard therapy for chronic stable angina and may play a future role in the management of acute coronary syndromes.
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PMID:Ranolazine: focusing on angina pectoris. 1662 59

Ranolazine is a selective inhibitor of the late sodium current relative to peak sodium channel current, and via this mechanism, it may decrease sodium-dependent intracellular calcium overload during ischemia and reperfusion. Ranolazine reduces the frequency of angina attacks, but there is little information on its effects on myocardial stunning after short-term ischemia. The objective of this study was to test the effects of ranolazine on left ventricular (LV) function and myocardial stunning after ischemia/reperfusion in rabbits. Myocardial stunning was induced in rabbits by 15 minutes of coronary artery occlusion (CAO) followed by 3 hours reperfusion. Ten minutes before CAO, rabbits were randomly assigned to vehicle (n = 15) or ranolazine (2 mg/kg bolus plus 60 microg/kg/min infusion, IV, n = 15). Myocardial stunning was assessed by LV 2-dimensional echocardiography using, as a marker of severity, ischemic free-wall fractional thickening (FWft; systolic wall thickness - diastolic wall thickness/diastolic wall thickness). Regional ejection fraction (EF) was also assessed. During CAO, FWft was depressed in both groups, indicating an ischemic insult (FWft was reduced from 0.62 +/- 0.05 at baseline to 0.10 +/- 0.04 in vehicle and from 0.73 +/- 0.05 to 0.26 +/- 0.07 in ranolazine, P < 0.05, ranolazine vs vehicle). After reperfusion, previously ischemic myocardium remained stunned; however, FWft recovered significantly better in ranolazine (0.51 +/- 0.05) than in vehicle (0.35 +/- 0.04, P = .027). Baseline EF was 0.65 +/- 0.02 in the ranolazine and 0.68 +/- 0.02 in vehicle (P = ns). During CAO, EF was reduced by 36% +/- 6% in vehicle versus only 20% +/- 6% in ranolazine (P < .05). At the end of reperfusion, EF remained depressed in both groups, but the reduction in the vehicle group (25% +/- 5%) was significantly worse than in ranolazine (9% +/- 4%, P = .017). Improvement in function was independent of necrosis (negligible) or differences in hemodynamics (no differences between groups). Ranolazine treatment reduced myocardial stunning following brief ischemia/reperfusion suggesting that inhibiting the late sodium channel current may be a novel approach to treating stunning independent of effects on hemodynamics.
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PMID:Ranolazine, an inhibitor of the late sodium channel current, reduces postischemic myocardial dysfunction in the rabbit. 1722 Apr 71

The sodium current in the heart is not a single current with a mono-exponential decay but rather a mixture of currents with different kinetics. It is not clear whether these arise from distinct populations of channels, or from modulation of a single population. A very slowly inactivating component, [(INa(P))] I(Na(P)) is usually about 1% of the size of the peak transient current [I(Na(T))], but is enhanced by hypoxia. It contributes to Na(+) loading and cellular damage in ischaemia and re-perfusion, and perhaps to ischaemic arrhythmias. Class I antiarrhythmic agents such as flecainide, lidocaine and mexiletine generally block I(NA(P)) more potently than block of I(Na(T)) and have been used clinically to treat LQT3 syndrome, which arises because mutations in SCN5A produce defective inactivation of the cardiac sodium channel. The same approach may be useful in some pathological situations, such as ischaemic arrhythmias or diastolic dysfunction, and newer agents are being developed with this goal. For example, ranolazine blocks I(Na(P)) about 10 times more potently than I(Na(T)) and has shown promise in the treatment of angina. Alternatively, the combination of I(Na(P)) block with K(+) channel block may provide protection from the induction of Torsades de Pointe when these agents are used to treat atrial arrhythmias (eg Vernakalant). In all of these scenarios, an understanding of the role of I(Na(P)) in cardiac pathophysiology, the mechanisms by which it may affect cardiac electrophysiology and the potential side effects of blocking I(Na(P)) in the heart and elsewhere will become increasingly important.
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PMID:The cardiac persistent sodium current: an appealing therapeutic target? 1807 2

Medical therapy is the standard background treatment for all patients with chronic stable angina. Studies show that antianginal therapies such as late sodium channel blockers (ranolazine), beta-blockers, calcium channel blockers, and nitrates dispensed alone or in combination can alleviate angina and angina-equivalent symptoms. For risk reduction of ischemic events, modification of coronary risk factors with lifestyle modification and medical therapy is the cornerstone. Effective risk modification strategies include lipid management, smoking cessation, diabetes control, weight management, nutritional enhancements, and physical activity. The pursuit of a more definitive treatment for chronic angina should be guided by the patient's clinical presentation, results of imaging-based risk-stratification evaluations, response to medical therapies, and patient preference. Revascularization by percutaneous coronary intervention or coronary artery bypass surgery may be recommended for patients who have persistent and intolerable symptoms despite optimal medical therapy and for those who are likely to have a survival benefit from revascularization based on the severity and location of the atherosclerotic lesions.
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PMID:Evaluating medical, percutaneous coronary intervention, and coronary artery bypass surgery options for chronic angina: an update of the revised guidelines. 1989 84

Chronic angina pectoris affects millions of patients every year. During the past 2 decades, advances in medical therapy have led to substantial reductions in the symptoms of angina. Nonetheless, many patients continue to experience persistent angina that causes debilitating symptoms and lifestyle changes. Moreover, many current therapeutic agents cause side effects that can induce substantial morbidity on their own. In major clinical trials, the drug ranolazine has been shown to bring symptomatic relief to large numbers of patients who have chronic angina. Herein, we review the physiology of the sodium channel; the pharmacology of ranolazine; clinical trials that support use of the drug; recent evidence about ranolazine's therapeutic effect on diastolic heart failure, glycemic control, and atrial fibrillation and other arrhythmias; officially approved clinical indications; and avenues of future study.
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PMID:Ranolazine: a new approach to treating an old problem. 2122 31

The late sodium current has been increasingly recognized for its mechanistic role in various cardiovascular pathologies, including angina pectoris, myocardial ischemia, atrial fibrillation, heart failure and congenital long QT syndrome. Although relatively small in magnitude, the late sodium current (I(NaL)) represents a functionally relevant contributor to cardiomyocyte (electro)physiology. Many aspects of I(NaL) itself are as yet still unresolved, including its distribution and function in different cell types throughout the heart, and its regulation by sodium channel accessory proteins and intracellular signalling pathways. Its complexity is further increased by a close interrelationship with the peak sodium current and other ion currents, hindering the development of inhibitors with selective and specific properties. Thus, increased knowledge of the intricacies of the complex nature of I(NaL) during distinct cardiovascular conditions and its potential as a pharmacological target is essential. Here, we provide an overview of the functional and electrophysiological effects of late sodium current inhibition on the level of the ventricular myocyte, and its potential cardioprotective and anti-arrhythmic efficacy in the setting of acquired and inherited ventricular dysfunction and arrhythmias.
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PMID:Late sodium current inhibition in acquired and inherited ventricular (dys)function and arrhythmias. 2329 67


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