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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cardiac pathologies are associated with increased late INa that contributes to the dysregulation of ion homeostasis and causes electrical and contractile dysfunction. This study was designed to test the hypothesis that an increased late sodium channel current (INa) leads to Ca2+ overload and left ventricular (LV) dysfunction, and thereby inhibition of late INa (e.g., by ranolazine) improves Ca2+ homeostasis and reduces LV dysfunction. Intracellular Ca2+ ([Ca2+]i) and LV function were measured simultaneously in rat isolated perfused hearts. Augmentation of late INa with sea anemone toxin-II (ATX-II, 12 nM) increased diastolic [Ca2+]i (d[Ca2+]i), and impaired LV mechanical function, but had no effect on [Ca2+]i transient amplitude. Although ranolazine (4 and 9 microM), an inhibitor of late INa, had no direct effects on d[Ca2+]i or LV function, it significantly reduced the deleterious effects of ATX-II. Global ischemia increased d[Ca2+]i and inhibited Ca2+ transient amplitude. During reperfusion, Ca2+ transient amplitude recovered fully, but d[Ca2+]i remained elevated and LV function was depressed, indicative of Ca2+ overload. Ranolazine (9 microM) reduced d[Ca2+]i accumulation during ischemia as well as reperfusion and improved recovery of LV function. These results show that augmentation of late INa with ATX-II or by ischemia is associated with diastolic Ca2+ overload and LV dysfunction. The beneficial effects of ranolazine in reducing Ca2+ overload and LV mechanical dysfunction during ischemia/reperfusion is consistent with the inhibition of late INa mechanism of action.
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PMID:Ranolazine decreases diastolic calcium accumulation caused by ATX-II or ischemia in rat hearts. 1702 25

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 optimal management of coronary artery disease is based on achieving two parallel objectives: 1) prevention of major cardiovascular events, and 2) resolution of symptoms. Traditional antianginal agents improve ischemic symptoms by reducing myocardial oxygen demand through modulation of heart rate, preload, and/or afterload. Ranolazine is a novel antianginal agent believed to relieve ischemia by reducing myocardial cellular sodium and calcium overload via inhibition of the late sodium current of the cardiac action potential. In three randomized double-blind trials in selected patients with chronic angina, ranolazine prolonged exercise duration and reduced symptoms when compared with placebo when given as either monotherapy or in combination with traditional antianginal pharmacotherapy. When evaluated in patients with non-ST-elevation acute coronary syndromes, ranolazine reduced recurrent ischemia but did not significantly reduce the risk of death or myocardial infarction at 1 year. Ranolazine complements traditional antianginal agents and offers clinicians a new option in the long-term treatment of patients with angina.
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PMID:Ranolazine in patients with angina and coronary artery disease. 1760 93

Traditional anti-anginal agents such as beta-blockers and nitrates improve symptoms of cardiac ischemia by affecting either blood pressure or heart rates. Despite aggressive therapy, many patients suffer persistent angina, and optimal therapy is limited by intolerance to traditional agents. Ranolazine, a novel anti-anginal agent that is approved for use in the US, is felt to improve ischemic symptoms by reducing myocardial cellular sodium and calcium overload via inhibition of the late sodium current (I(Na)) of the cardiac action potential. Several Phase-III trials in patients with chronic angina have demonstrated that ranolazine improves exercise tolerance and reduces ischemic symptoms as compared with placebo. In the largest evaluation of ranolazine, the MERLIN-TIMI 36 trial (Metabolic Efficiency with Ranolazine for Less Ischemia in non ST elevation acute coronary syndrome), ranolazine did not reduce the risk of death or recurrent myocardial infarction in patients with non-ST-elevation acute coronary syndromes, but it did improve ischemic symptoms over the subsequent year of therapy. Thus, ranolazine offers clinicians a new therapy in the long-term treatment of patients with chronic angina.
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PMID:Ranolazine in patients with coronary artery disease. 1771 67

Ranolazine is a piperazine derivative believed to reduce anginal symptoms by preventing ischemia-mediated sodium and calcium overload in myocardial cells through inhibition of the late sodium current (late INa). Three small studies demonstrated the antianginal efficacy of ranolazine alone and in combination with betablockers or calcium channel blockers on conventional end points such as total exercise duration and time to ischemia/angina on a treadmill; however, questions of safety related to QT prolongation, efficacy in women and potential utility in higher risk populations remained. Metabolic Efficiency with Ranolazine for Less Ischemia in Non-ST Elevation Acute Coronary Syndromes-Thrombolysis in Myocardial Infarction (MERLIN-TIMI) 36 was a large randomized, double-blind, placebo-controlled trial, which evaluated the efficacy and safety of ranolazine initiated acutely and continued as chronic therapy following a non-ST-segment elevation acute coronary syndrome event. A total of 6560 patients were randomized 1:1 to ranolazine or placebo; the primary efficacy end point of the trial was a composite of cardiovascular death, myocardial infarction or recurrent ischemia. The key safety end points were death from any cause and symptomatic documented arrhythmia. Although statistically significant differences between the ranolazine and placebo groups were not reached in the primary efficacy analysis or in the major secondary outcome end point analyses (cardiovascular death, myocardial infarction or severe recurrent ischemia), the individual component of recurrent ischemia was significantly reduced by ranolazine, and ranolazine was demonstrated to be safe.
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PMID:Metabolic efficiency with ranolazine for less ischemia in non-ST elevation acute coronary syndromes (MERLIN TIMI-36) study. 1809 3

Chronic Angina resistant to medical treatment with hemodynamically acting agents is a major problem in clinical setup. For such patients, large number of clinical trials have documented the beneficial effect of Ranolazine. It acts as an anti-anginal agent that controls myocardial ischemia through intracellular metabolic changes. Ranolazine is a partial fatty acid oxidation inhibitor which shifts cardiac energy metabolism from fatty acid oxidation to glucose oxidation. Since the oxidation of glucose requires less oxygen than the oxidation of fatty acids, ranolazine can help maintain myocardial function in times of ischemia. In addition, ranolazine has minimal effect on blood pressure and heart rate. Ranolazine, by inhibiting cellular ionic channels, prolongs the corrected QT interval. However, ranolazine has not yet been associated with any incidences of ventricular arrhythmia. Other possible mechanism by which Ranolazine could act is by reducing the formation of reactive oxygen species (ROS) and improves reperfusion mechanical function. Ranolazine has been approved by US FDA for the treatment of chronic angina pectoris in combination with amlodipine, beta-blockers or nitrates in patients who do not show adequate response to other anti-anginals. Ranolazine is a metabolic modulator that is being developed by CV Therapeutics (CVT), under license from Roche (formerly Syntex), as a potential treatment for angina. Ranolazine is available as brand name 'Ranexa' as extended release oral tablets. This review focuses on the clinical effects, the mechanism of actions, drug interactions and beneficial effects of Ranolazine in chronic angina and other cardiometabolic disorders.
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PMID:Ranolazine, a partial fatty acid oxidation inhibitor, its potential benefit in angina and other cardiovascular disorders. 1822 Nov 1

William Heberden in 1772 published "some account of the disorder of the breast" which contains the essential elements of angina pectoris as we understand it today. The number of existing cases in the U.S. population today is 6.4 million. Myocardial ischemia manifested by angina pectoris can be either acute or chronic. Patients with chronic stable angina will be the focus of this supplement. The majority of patients are symptomatic but approximately 25% can be asymptomatic. The clinical manifestations of myocardial ischemia generally are chest discomfort, arrhythmias, and LV dysfunction. Myocardial ischemia is a result of imbalance between myocardial oxygen supply and myocardial oxygen demand. High grade coronary stenosis are the usual cause of decreased oxygen supply. The classic hemodynamic factors increasing myocardial oxygen demand include hypertension and increased heart rate due to tachyarrhythmias of any etiology. Exertion is the usual precipitating cause of chronic myocardial ischemia. New information has come forward indicating that myocardial ischemia is associated with disruption of cellular sodium and calcium homeostasis. Ischemia results in a rise of intracellular sodium concentration and thus sodium overload which then activates the sodium calcium exchanger and leads to increased intracellular calcium. When this occurs there is electrical instability and mechanical dysfunction which increases oxygen demand and decreases oxygen supply. The compound Ranolazine is thought to selectively inhibit the late sodium current and attenuates the abnormalities of ventricular repolarization and contractility associated with myocardial ischemia. This compound is the first new class of anti-anginal medication approved in 25 years which may provide physicians with additional therapy for chronic stable angina along with the other anti-angina agents, beta blockers, calcium antagonists and nitrates.
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PMID:Re-thinking angina. 1837 24

Ranolazine inhibits the late Na current and is proposed to reduce angina by decreasing [Na]i during ischemia, thereby reducing Ca influx via Na/Ca exchange (NCX). We sought to test this hypothesis and to determine whether oxidative stress during simulated-demand ischemia activates the late Na current. We measured [Ca]i and [Na]i in rabbit ventricular myocytes by flow cytometry during metabolic inhibition (MI) with 2 mM cyanide and 0 mM glucose at 37 degrees C plus pacing (P) at 0.5 Hz (P-MI), and in P-MI + 1, 10, or 50 microM ranolazine. In the clinically relevant concentration range (1-10 microM), ranolazine decreased Na and Ca loading and the development of myocyte contracture. P-MI caused an increase in fluorescence of the oxidative radical probe CM-H2DCFDA, which was inhibited by the radical scavenger Tiron 20 mM. The NCX inhibitor KB-R7943 (10 microM) and Tiron 20 mM reduced the rise in [Ca]i during P-MI and eliminated the effect of 10 microM ranolazine on [Ca]i. These results indicate that oxidative stress increases the late Na current during MI. Inhibition of the resulting increase in Na and Ca loading and contracture seems to account for the observed antiischemia effects of ranolazine.
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PMID:Ranolazine inhibits an oxidative stress-induced increase in myocyte sodium and calcium loading during simulated-demand ischemia. 1839 79

There is increasing evidence that the late sodium current of the sodium channel in myocytes plays a critical role in the pathophysiology of myocardial ischemia and thus is a potential therapeutic target in patients with ischemic heart disease. Ranolazine, an inhibitor of the late sodium current, reduces the frequency and severity of anginal attacks and ST-segment depression in humans, and unlike other antianginal drugs, ranolazine does not alter heart rate or blood pressure. In experimental animal models, ranolazine has been shown to reduce myocardial infarct size and to improve left ventricular function after acute ischemia and chronic heart failure. This article reviews published data describing the role of late sodium current and its inhibition by ranolazine in clinical and experimental studies of myocardial ischemia.
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PMID:Late sodium current inhibition as a new cardioprotective approach. 1846 46

It has been suggested that ranolazine protects the ischemic/reperfused heart by reducing diastolic wall pressure during ischemia. However, there is limited information regarding the effect of ranolazine on the anatomic zone of no-flow in a model of acute myocardial occlusion/reperfusion. Before coronary artery occlusion (CAO), open-chest anesthetized rabbits were assigned to vehicle or ranolazine. Hearts received 60 minutes of CAO and 3 hours reperfusion. Ischemic risk zone was comparable in the 2 groups. Ranolazine significantly reduced infarct size. There was a non-significant trend for the no-reflow defect to be smaller in the ranolazine group. Regional myocardial blood flow was similar in both groups in the risk zone during ischemia and at 3 hours reperfusion. Heart rates were similar in both groups, whereas mean arterial pressure was reduced in the ranolazine group. While ranolazine was effective in reducing myocardial infarct size, the mechanism by which it did this was independent of improving perfusion during either ischemia or reperfusion, suggesting that ranolazine's effect of reducing infarct size involves alternative mechanisms.
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PMID:The antianginal agent, ranolazine, reduces myocardial infarct size but does not alter anatomic no-reflow or regional myocardial blood flow in ischemia/reperfusion in the rabbit. 1862 5


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