Myocardial carnitine in end-stage congestive heart failure

Metabolome Profiling in the Plasma of Dogs with Idiopathic Dilated Cardiomyopathy: A Multiplatform Mass-Spectrometry-Based Approach

Dilated cardiomyopathy is one of the important diseases in dogs and humans. The second most common cause of heart failure in dogs is idiopathic dilated cardiomyopathy (iDCM), which results in heart failure or sudden cardiac death due to arrhythmia. This study aimed to determine changes in the plasma metabolome of dogs with iDCM compared to healthy dogs. For that purpose, a multiplatform mass-spectrometry-based approach was used. In this study, we included two groups of dogs: 12 dogs with iDCM and 8 healthy dogs. A total of 272 metabolites were detected in the plasma samples of dogs by combining three approaches but four MS-based platforms (GC-MS, LC-MS (untargeted), LC-MS (targeted), and FIA-MS (targeted) methods). Our findings demonstrated changes in the canine plasma metabolome involved in the development of iDCM, including the different concentrations of amino acids, biogenic amines, acylcarnitines, triglycerides and diglycerides, sphingomyelins, and organic acids. The results of this study will enable the detection and monitoring of pathophysiological mechanisms involved in the development of iDCM in the future.

Quantitative Profiling of Serum Carnitines Facilitates the Etiology Diagnosis and Prognosis Prediction in Heart Failure

BACKGROUND

The perturbation of fatty acid metabolism in heart failure (HF) has been a critical issue. It is unclear whether the amounts of circulating carnitines will benefit primary etiology diagnosis and prognostic prediction in HF. This study was designed to assess the diagnostic and prognostic values of serum carnitine profiles between ischemic and non-ischemic derived heart failure.

METHODS

HF patients (non-ischemic dilated cardiomyopathy: DCM-HF, n = 98; ischemic heart disease: IHD-HF, n = 63) and control individuals (n = 48) were enrolled consecutively. The serum carnitines were quantitatively measured using the UHPLC-MS/MS method. All patients underwent a median follow-up of 28.3 months. Multivariate Cox regression analysis was performed during the prognosis evaluation.

RESULTS

Amongst 25 carnitines measured, all of them were increased in HF patients, and 20 acylcarnitines were associated with HF diagnosis independently. Seven acylcarnitines were confirmed to increase the probability of DCM diagnosis independently. The addition of isobutyryl-L-carnitine and stearoyl-L-carnitine to conventional clinical factors significantly improved the area under the receiver operating characteristic curve (ROC) from 0.771 to 0.832 (p = 0.023) for DCM-HF diagnosis (calibration test for the composite model: Hosmer-Lemeshow χ² = 7.376, p = 0.497 > 0.05). Using a multivariate COX survival analysis adjusted with clinical factors simultaneously, oleoyl L-carnitine >300 nmol/L (HR = 2.364, 95% CI = 1.122-4.976, p = 0.024) and isovaleryl-L-carnitine <100 nmol/L (HR = 2.108, 95% CI = 1.091-4.074, p = 0.026) increased the prediction of all-cause mortality independently, while linoleoyl-L-carnitine >420 nmol/L, succinyl carnitine >60 nmol/L and isovaleryl-L-carnitine <100 nmol/L increased the risk of HF rehospitalization independently.

CONCLUSIONS

Serum carnitines could not only serve as diagnostic and predictive biomarkers in HF but also benefit the identification of HF primary etiology and prognosis.

Metabolic Reprogramming, Gut Dysbiosis, and Nutrition Intervention in Canine Heart Disease

This review provides a state-of-the-art overview on recent advances in systems biology in canine cardiac disease, with a focus on our current understanding of bioenergetics and amino acid metabolism in myxomatous mitral valve disease (MMVD). Cross-species comparison is drawn to highlight the similarities between human and canine heart diseases. The adult mammalian heart exhibits a remarkable metabolic flexibility and shifts its energy substrate preference according to different physiological and pathological conditions. The failing heart suffers up to 40% ATP deficit and is compared to an engine running out of fuel. Bioenergetics and metabolic readaptations are among the major research topics in cardiac research today. Myocardial energy metabolism consists of three interconnected components: substrate utilization, oxidative phosphorylation, and ATP transport and utilization. Any disruption or uncoupling of these processes can result in deranged energy metabolism leading to heart failure (HF). The review describes the changes occurring in each of the three components of energy metabolism in MMVD and HF. It also provides an overview on the changes in circulating and myocardial glutathione, taurine, carnitines, branched-chain amino acid catabolism and tryptophan metabolic pathways. In addition, the review summarizes the potential role of the gut microbiome in MMVD and HF. As our knowledge and understanding in these molecular and metabolic processes increase, it becomes possible to use nutrition to address these changes and to slow the progression of the common heart diseases in dogs.

High-resolution metabolomics study revealing l-homocysteine sulfinic acid, cysteic acid, and carnitine as novel biomarkers for high acute myocardial infarction risk

BACKGROUND

Identifying changes in serum metabolites before the occurrence of acute myocardial infarction (AMI) is an important approach for finding novel biomarkers of AMI.

METHODS

In this prospective cohort study, serum samples obtained from patients at risk of AMI (n = 112) and non-risk controls (n = 89) were tested using high-resolution metabolomics (HRM). Partial least-squares discriminant analysis (PLS-DA), along with univariate analysis using a false discovery rate (FDR) of q = 0.05 were performed to discriminate metabolic profiles and to determine significantly different metabolites between healthy control and AMI risk groups.

RESULTS

PLS-DA significantly separated the AMI risk sera from control sera. The metabolites associated with amino acid biosynthesis, 2-oxocarboxylic acid, tryptophan, and amino sugar and nucleotide sugar metabolism pathways were mainly elevated in patients at risk of AMI. Further validation and quantification by MS/MS showed that tryptophan, carnitine, L-homocysteine sulfinic acid (L-HCSA), and cysteic acid (CA) were upregulated, while L-cysteine and L-cysteine sulfinic acid (L-CSA) were downregulated, specifically among AMI risk sera. Additionally, these discriminant metabolic profiles were not related to hypertension, smoking or alcoholism.

CONCLUSION

In conclusion, detecting upregulated L-HCSA and CA along with carnitine among patients at risk for AMI could serve as promising non-invasive biomarkers for early AMI detection.

Global metabolomics analysis of serum from humans at risk of thrombotic stroke

We aimed to determine the serum concentrations of altered compounds to understand the changes in metabolism and pathophysiology that occur prior to thrombotic stroke.

l-Carnitine and heart disease

Cardiovascular disease (CVD) is a key cause of deaths worldwide, comprising 15-17% of healthcare expenditure in developed countries. Current records estimate an annual global average of 30 million cardiac dysfunction cases, with a predicted escalation by two-three folds for the next 20-30years. Although β-blockers and angiotensin-converting-enzymes are commonly prescribed to control CVD risk, hepatotoxicity and hematological changes are frequent adverse events associated with these drugs. Search for alternatives identified endogenous cofactor l-carnitine, which is capable of promoting mitochondrial β-oxidation towards a balanced cardiac energy metabolism. l-Carnitine facilitates transport of long-chain fatty acids into the mitochondrial matrix, triggering cardioprotective effects through reduced oxidative stress, inflammation and necrosis of cardiac myocytes. Additionally, l-carnitine regulates calcium influx, endothelial integrity, intracellular enzyme release and membrane phospholipid content for sustained cellular homeostasis. Carnitine depletion, characterized by reduced expression of "organic cation transporter-2" gene, is a metabolic and autosomal recessive disorder that also frequently associates with CVD. Hence, exogenous carnitine administration through dietary and intravenous routes serves as a suitable protective strategy against ventricular dysfunction, ischemia-reperfusion injury, cardiac arrhythmia and toxic myocardial injury that prominently mark CVD. Additionally, carnitine reduces hypertension, hyperlipidemia, diabetic ketoacidosis, hyperglycemia, insulin-dependent diabetes mellitus, insulin resistance, obesity, etc. that enhance cardiovascular pathology. These favorable effects of l-carnitine have been evident in infants, juvenile, young, adult and aged patients of sudden and chronic heart failure as well. This review describes the mechanism of action, metabolism and pharmacokinetics of l-carnitine. It specifically emphasizes upon the beneficial role of l-carnitine in cardiomyopathy.

Myocardial Response to Pretreatment with L-Carnitine in Patients with Cardiac Valve Replacement

Twenty-one patients undergoing mitral valve replacement (MVR) with either isolated or combined valvular procedure were investigated to determine the ef fect of randomized and prospective administration of L-carnitine (car) chloride on myocardial function. Carnitine chloride (1800 mg/day, for seven consecu tive days just prior to MVR) was given orally to 9 patients (car-treated group) who were compared with 12 car-untreated patients (control group) subjected to the same procedure. Valve replacement was performed using the Bjork-Shiley mechanical prosthesis in aortic and mitral position and bioprosthesis in tricuspid position in both groups under cardiopulmonary bypass (CPB) associated with cold potassium-magnesium cardioplegia and systemic hypothermia. Preopera tive and intraoperative clinical profile (age, functional class, duration of aortic clamp and CPB, and level of hypothermia) was well matched in both groups. Free, short-chain acyl, long-chain acyl, and total Car were measured in the papil lary muscle excised adjacent to the free wall of the left ventricle at the time of valvular surgery. Heart rate and mean arterial pressure did not differ between the two groups. Cardiac index was 3.44 ± 0.08 and 3.82 ± 0.13 L/m2/min in the control and car-treated groups, respectively, (p < 0.05). Dobutamine (DOB) infusion rate was 8.55 ± 0.73 and 5.57 ± 0.95 μg/kg/min in the control and car-treated groups, respectively (p < 0.05). Left ventricular stroke work index (LVSWI)/DOB ratio was 4.50 ± 0.65 and 8.16 ± 1.72 g*m/m 2/beat/unit of DOB, in the control and car-treated groups, respectively (p < 0.05). Long-chain acyl carnitine was 0.224 ± 0.031 and 0.460 ± 0.096 nmoL/mg noncollagenous protein in the control and the car-treated groups, respectively (p<0.05). LVSWI/DOB ratio was well correlated with long-chain acyl carnitine in the tis sue, r = 0.74, n = 18, p<0.001.

These findings suggest that pretreatment with L-carnitine chloride appears to be effective in improving myocardial function in the early phase of reperfu sion following surgery and that long-chain acyl carnitine may play a key role in the enhancement of carnitine-meditated mitochondrial metabolic process.

Carnitine deficiency in patients with coeliac disease and idiopathic dilated cardiomyopathy

BACKGROUND AND AIMS

Idiopathic dilated cardiomyopathy (IDCM) and coeliac disease (CD) are two pathological conditions which may lead, by different mechanisms, to malabsorption of various micronutrients, including carnitine, active in cardiac metabolism. The aim of the present investigation was primarily to evaluate differences in serum concentrations of total carnitine between IDCM patients and patients with IDCM associated with CD and then also to evaluate, in the latter, the effect of a gluten-free diet on serum concentrations of total carnitine.

METHOD AND RESULTS

Serum carnitine was determined by enzymatic spectrophotometric assay in three groups of individuals: group A, 10 patients (5 males, 5 females), mean age 46.5+/-10.8 years, presenting isolated IDCM; group B, 3 patients (2 males, 1 female), mean age 34+/-8 years, with IDCM+CD; and group C, 10 healthy subjects (5 males, 5 females), mean age 38.6+/-11.1 years. All patients with IDCM belonged to class NYHA I-II. Mean concentrations of total serum carnitine in the group of patients with isolated IDCM (group A) were found to be lower than in the controls (group C). The concentrations in patients with IDCM associated with CD (group B) were lower than in the control group and also lower than in the isolated IDCM (group A). After 2 years on a gluten-free diet, patients presenting IDCM associated with CD showed a progressive increase in mean serum carnitine levels compared to values observed prior to the diet.

CONCLUSIONS

Patients presenting IDCM associated with CD show a greater decrease in serum total carnitine levels than patients presenting the isolated form of IDCM. A gluten-free diet, in these patients, leads to a progressive increase in serum levels of this substance.

Metabolic and structural abnormalities in dogs with early left ventricular dysfunction induced by incessant tachycardia

OBJECTIVE

To assess morphologic and metabolic abnormalities in dogs with early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP).

ANIMALS

7 Beagles.

PROCEDURE

Plasma carnitine concentrations were measured before and after development of ELVD induced by RRVP. At the same times, transvenous endomyocardial biopsy was performed, and specimens were submitted for determination of myocardial carnitine concentrations and histologic, morphometric, and ultrastructural examination.

RESULTS

In 4 dogs in which baseline plasma total carnitine concentration was normal, RRVP induced a decrease in myocardial total and free carnitine concentrations and an increase in myocardial esterified carnitine concentration. In 3 dogs in which baseline plasma total carnitine concentration was low, plasma and myocardial carnitine concentrations were unchanged after pacing. Structural changes associated with pacing included perinuclear vacuolization in 3 dogs. Morphometric analyses indicated there was a decrease in myofiber cross-sectional diameter and area following pacing. Electron microscopy revealed changes in myofibrils and mitochondria following pacing.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that moderate to severe alterations in myocyte cytoarchitecture are present in dogs with ELVD induced by RRVP and that in dogs with normal plasma carnitine concentrations, myocardial carnitine deficiency may be a biochemical marker of ELVD. Results also indicated that transvenous endomyocardial biopsy can be used to evaluate biochemical and structural myocardial changes in dogs with cardiac disease.

Plasma carnitine levels as a marker of impaired left ventricular functions

L-Carnitine plays a role in the utilization of fatty acids and glucose in the myocardium. Previous studies have indicated carnitine deficiency in patients with congestive heart failure. However, the extent of altered carnitine metabolism and left ventricular function is not fully determined. This study is designed to determine if plasma L-carnitine levels can serve as a marker for impaired left ventricular function in patients with congestive heart failure. To test this hypothesis, plasma and urinary levels of L-carnitine were measured in 30 patients with congestive heart failure (CHF) and in 10 control subjects. CHF was due to dilated cardiomyopathy (DCM) and rheumatic heart disease (RHD). Cardiac functions such as percentage of fractional shortening (%FS), ejection fraction (EF), left ventricular mass index (LVMI), were determined by echocardiography. All patients and control subjects had normal renal functions. Plasma carnitine was significantly higher in patients with DCM (37.05+/-7.62, p < 0.0001) and with RHD (47.2+/-8.04, p < 0.0001) vs. the control subjects (14.4+/-5.30 mg/L). Urinary carnitine was significantly higher in DCM (49.13+/-14.11, p < 0.0001) and in RHD 43.53+/-15.5, p < 0.0001), than the control (25.1+/-5.78 mg/L). Plasma carnitine level correlated significantly with impaired left ventricular systolic functions in these patients: % FS < 25 % (r = -0.38 and p = 0.038), EF < 0.55 (r = -0.502 and p = 0.005) and LMVI > 124 gm/m2 (r = 0.436, and p = 0.016). These data suggest that elevated plasma and urinary carnitine levels in patients with CHF could serve as a marker for myocardial damage and impaired left ventricular functions.

The effects of L-carnitine treatment on left ventricular function and erythrocyte superoxide dismutase activity in patients with ischemic cardiomyopathy

We studied the effects of L-carnitine on left ventricular systolic function and the erythrocyte superoxide dismutase activity in 51 patients with ischemic cardiomyopathy. They all previously were under the treatment of angiotensin-converting enzyme inhibitor, digitalis and diuretics. Patients were randomized into two groups. In group I (n=31), 2 g/day L-carnitine was added to therapy. L-Carnitine was not given to the other 20 patients (Group II). In group I (mean age 64.3+/-7.8 years), 27 of the patients were men, and four were women. In group II (mean age 66.2+/-8.7 years), 17 of the patients were men, and three were women. Twenty age-matched healthy subjects (mean age: 60.1+/-5.3 years) constituted the control group. In each group, left ventricular ejection fraction (LVEF) by echocardiography and red cell superoxide dismutase activity by spectrophotometric method were measured initially and after 1 month of randomisation. Compared with normal healthy subjects (n=20), patients (n=51) had significantly higher red cell SOD activity (5633+/-1225 vs. 3202+/-373 U/g Hb, P<0.001). At the end of 1 month of L-carnitine therapy, red cell SOD activity showed an increase in group I (5918+/-1448 to 7218+/-1917 U/g Hb, P<0.05). In group II, red cell SOD activity showed no significant change after 1 month of randomisation (5190+/-545 to 5234+/-487 U/g Hb, P=0. 256). One month after randomisation there was a significant increase in LVEF in both groups I and II (37.8-42.3%, P<0.001 in group I; 41. 5-43.8%, P<0.001 in group II). The improvement in LVEF was more significant in the L-carnitine group (4.5% vs. 2.3%, P<0.01). We conclude that, as a sign of increased free radical production, superoxide dismutase activity was further increased in patients with L-carnitine treatment. L-Carnitine treatment in combination with other traditional pharmacological therapy might have an additive effect for the improvement of left ventricular function in ischemic cardiomyopathy.

Three-year survival of patients with heart failure caused by dilated cardiomyopathy and L-carnitine administration

We examined the efficacy of long-term L-carnitine administration for the treatment of heart failure caused by dilated cardiomyopathy in adult patients. To accomplish this, we studied 80 patients with moderate to severe heart failure (New York Heart Association classification III to IV) caused by dilated cardiomyopathy. This article reports on the nearly 3 years of follow-up data on patient mortality. Primary results will be published in the future. After a period of stable cardiac function up to 3 months, patients were randomly assigned to receive either L-carnitine (2 g/d orally) or placebo. There were no statistical differences between the 2 groups at baseline examination in clinical and hemodynamic parameters, such as ejection fraction, Weber classification, maximal time of cardiopulmonary exercise test, peak VO(2) consumption, arterial and pulmonary blood pressure, and cardiac output. After a mean of 33.7 +/- 11.8 months of follow-up (range 10 to 54 months), 70 patients were in the study: 33 in the placebo group and 37 in the L-carnitine group. At the time of analysis, 63 patients were alive. There were 6 deaths in the placebo group and 1 death in the L-carnitine group. Survival analysis with the Kaplan-Meier method showed that patients' survival was statistically significant (P <.04) in favor of the L-carnitine group. L-carnitine appears to possess considerable potential for the long-term treatment of patients with heart failure attributable to dilated cardiomyopathy.

Carnitine and its derivatives in cardiovascular disease

Carnitine and its derivative propionyl-L-carnitine are endogenous cofactors which enhance carbohydrate metabolism and reduce the intracellular buildup of toxic metabolites in ischemic conditions. The carnitines have been, and are being used in a spectrum of diseases including multiple cardiovascular conditions. These include angina, acute myocardial infarction, postmyocardial infarction, congestive heart failure, peripheral vascular disease, dyslipidemia, and diabetes. Most published data on carnitine, propionyl-L-carnitine, and other carnitine congeners are favorable but the clinical trials have been relatively small. In currently used doses, these substances are virtually devoid of significant side effects.

Long-term 1-carnitine treatment prolongs the survival in rats with adriamycin-induced heart failure

BACKGROUND

The most serious consequence of heart failure is the shortened life expectancy, which may be associated with myocardial energy starvation.

METHODS AND RESULTS

Eight-week-old male Sprague-Dawley rats received 6 intraperitoneal injections of adriamycin (group A: total dose; 15 mg/kg body weight) or vehicle (group C) over 2 weeks. Rats then received either 272 mg/kg daily of oral 1-carnitine (A-LC and C-LC groups) or saline (A-S and C-S groups) for 6 weeks. The cumulative mortality rate in the A-LC group was significantly lower than in the A-S group (13 vs 42%, P = .028). Myocardial levels of high-energy phosphate compounds (ATP and creatine phosphate) and fatty acid metabolites (free carnitine, short-chain and long-chain acylcarnitine, and long-chain acyl CoA) in the left ventricle were measured the day after the last dose of drug or vehicle was administered. ATP was decreased by 73%, creatine phosphate by 61%, free carnitine by 52%, short-chain acylcarnitine by 48%, and long-chain acylcarnitine by 56% in the A-S group compared to the C-S group. Long-chain CoA was increased by 168% in the A-S group. Levels of myocardial high-energy phosphate compounds and fatty acid metabolites were near normal in adriamycin- and 1-carnitine-treated rats.

CONCLUSIONS

Preservation of the myocardial level of carnitine by 1-carnitine treatment prolonged survival of rats with adriamycin-induced failure by improving the myocardial metabolism of fatty acids.

Cardiac energy metabolism at several stages of adriamycin-induced heart failure in rats

To evaluate the changes in myocardial energy metabolism in the progressively failing myocardium, we measured myocardial level of adenosine triphosphate (ATP) using high-performance liquid chromatography (HPLC), and levels of lactate, alanine and free carnitine using 1H-nuclear magnetic resonance (NMR) spectroscopy in rats injected with adriamycin. The drug was injected intraperitoneally 2.5 mg/kg 6 times over a period of 2 weeks. Measurements were obtained 1 day (1 d), 3 weeks (3 w) and 6 weeks (6 w) after the last injection. No deaths were observed until the end of the 3rd week. The cumulative mortality rate 6 weeks after the last injection was 48%. ATP and free carnitine levels were not significantly changed at 1 d, while myocardial lactate was increased by 33% from the control values (P < 0.05). Lactate levels were reduced significantly, but not progressively, at 3 w (31% of control values) and at 6 w (69% of control values). Similar changes were observed in alanine levels. Free carnitine levels were progressively decreased at 3 w (74% of control values) and at 6 w (57% of control values). Changes in ATP levels paralleled those of free carnitine. Data suggest that a decrease in the myocardial level of free carnitine may be involved in progression of the heart failure induced by adriamycin in rats.

A randomised, double-blind, placebo-controlled trial of L-carnitine in suspected acute myocardial infarction

In a randomised, double-blind placebo-controlled trial, the effects of the administration of oral L-carnitine (2 g/day) for 28 days were compared in the management of 51 (carnitine group) and 50 (placebo group) patients with suspected acute myocardial infarction. At study entry, the extent of cardiac disease, cardiac enzymes and lipid peroxides were comparable between the groups, although both groups showed an increase in cardiac enzymes and lipid peroxides. At the end of the 28-day treatment period, the mean infarct size assessed by cardiac enzymes showed a significant reduction in the carnitine group compared to placebo. Electrocardiographic assessment of infarct size revealed that the QRS-score was significantly less in the carnitine group compared to placebo (7.4 +/- 1.2 vs 10.7 +/- 2.0), while serum aspartate transaminase and lipid peroxides showed significant reduction in the carnitine group. Lactate dehydrogenase measured on the sixth or seventh day following infarction showed a smaller rise in the carnitine group compared to placebo. Angina pectoris (17.6 vs 36.0%), New York Heart Association class III and IV heart failure plus left ventricular enlargement (23.4 vs 36.0%) and total arrhythmias (13.7 vs 28.0%) were significantly less in the carnitine group compared to placebo. Total cardiac events including cardiac deaths and nonfatal infarction were 15.6% in the carnitine group vs 26.0% in the placebo group. It is possible that L-carnitine supplementation in patients with suspected acute myocardial infarction may be protective against cardiac necrosis and complications during the first 28 days.

Urinary carnitine excretion in patients with heart failure

To evaluate the fatty acid metabolism in heart failure, the semiquantitative analysis of urinary free carnitine and acylcarnitine was made by fast atom bombardment mass spectrometry (FABMS) in 22 patients (mean age 67.3 years) with heart failure and 19 age-matched healthy controls (average age 60.4 years). Urinary excretion of free carnitine was 0.20 +/- 0.118 ratio/mg creatinine in the healthy controls and 1.32 +/- 1.170 ratio/mg creatinine in the patients with heart failure. The latter value was significantly higher (p < 0.01). Patients with heart failure were classified into two groups according to the urinary free carnitine concentration. One was the high excretion group (2.19 +/- 0.102 ratio/mg creatinine, 12 cases) and the other was the low excretion group (0.37 +/- 0.212 ratio/mg creatinine, 10 cases). In the high excretion group, urinary acetylcarnitine was also increased, but no significant abnormalities were observed in the urinary organic acid profile. In the high group, 1 patient was classified as NYHA class III and 11 as NYHA class IV. Four patients died in the hospital. In the low excretion group, five patients were classified as NYHA class III and five as NYHA class IV. Only one patient died in the hospital. In the high group, patients with severe and prolonged heart failure tended to maintain higher values of urinary free carnitine. We could not find any abnormalities in fatty acid metabolism in patients with heart failure, but it is suspected that the patients who excrete large amounts of free carnitine into the urine, namely the patients with severe heart failure, have some possibility of carnitine deficiency.

The myocardial distribution and plasma concentration of carnitine in patients with mitral valve disease

The myocardial distribution and concentration of carnitine and its fractions was studied in 11 patients with mitral valve disease not associated with congestive heart failure (CHF). The plasma concentration of carnitine was found to be identical to the normal values documented in the literature. The left ventricular papillary muscle had the highest concentrations of total, short-acyl, long-acyl, and free carnitine, being significantly higher than those of the right ventricle, while the right atrial appendage had the lowest values of all fractions of carnitine. The proportion of long-acyl carnitine to total carnitine was significantly greater in the left ventricle than in either the right atrium or the atrial septum, and other carnitine fractions were identical in all cardiac chambers. Our results suggest that in the compensated heart with mitral valve disease, carnitine and its fractions are greatest in the left ventricle in the muscles of all cardiac chambers, and that long-acyl carnitine is most likely to be linked to the cardiac muscle demanding a higher cardiac performance.

Myocardial carnitine metabolism in congestive heart failure induced by incessant tachycardia

Persistent tachycardia induces congestive heart failure (CHF), but the mechanism(s) of progressive ventricular dysfunction is (are) unclear. This study was designed to define possible metabolic causes of myocardial dysfunction in rapid ventricular pacing induced CHF. Twelve adult mongrel dogs were paced to 250 beats/min for 19 days. Plasma carnitine, norepinephrine and renin were measured at 0, 1, 2, and 3 weeks. Myocardial high energy phosphates, carnitine, glycogen, glucose, non-collagenous protein and collagen were measured at 19 days. Cardiac output, arterial pressure and pulmonary wedge pressure, measured at baseline and with CHF, showed a decrease in cardiac output and increase in pulmonary wedge pressure. Neurohumoral activation was evident by progressively increasing plasma norepinephrine and renin activity and depletion of myocardial norepinephrine. Plasma free carnitine rose significantly from 12.6 +/- 2.0 control to 28.3 +/- 3.8 nmol/ml at 19 days (p < 0.001), whereas myocardial total carnitine was lower in paced than in control dogs (6.0 +/- 1.9 vs. 14.1 +/- 3.5 nmol/mg non-collagenous protein, p < 0.001). Myocardial ATP ATP and ADP were unchanged, while AMP decreased 22%, and creatine phosphate decreased 30% compared to control animals. Myocardial glucose was normal but glycogen was decreased 54% (p < 0.005). The low myocardial carnitine and elevated plasma carnitine in pacing induced CHF suggests altered carnitine transport or membrane integrity.

The metabolic syndrome and signal transduction of gene expression

Epidemiological studies have clearly shown that the so-called metabolic syndrome which is linked to insulin resistance and a reduced glucose utilization of muscle represents an important risk factor for cardiovascular disease. However, only little is known of the intracellular consequences of insulin resistance. An important feature of an altered substrate utilization is related to signal transduction of gene expression. For the example of myosin heavy chain expression, it is shown that metabolic signals exist which reflect the fuel flux and substrate utilization of the heart muscle cell. The signals were characterized in functional states of the heart associated with altered metabolic influences (fasting, diabetes, sucrose feeding, increased calorie intake, carnitine palmitoyltransferase inhibition). In the pressure-overloaded heart, metabolic interventions which are expected to increase glucose utilization (sucrose feeding, captopril treatment) have a pronounced effect. Although a link with gene expression remains to be established, it should be noted that the sarcoplasmic reticulum Ca(2+)-pump activity seems to be affected in a functionally comparable manner. It is concluded that metabolic signals alter the protein phenotype of heart muscle and it is expected that a deranged signal transduction affects, not only the heart, but also vascular muscle.