Effects of L-carnitine on erythrocyte acyl-CoA, free CoA, and glycerophospholipid acyltransferase in uremia

Comparison of vitamin e and L-carnitine, separately or in combination in patients with intradialytic complications

BACKGROUND

The most common complications during dialysis are hypotension and muscle cramps. There are many strategies to prevent and treat these complications.

OBJECTIVES

The aim of this study is to evaluate effects of vitamin E and L-carnitine supplementation alone and in combination on intradialytic complications.

PATIENTS AND METHODS

In a prospective study, 20 patients with end stage renal disease on chronic hemodialysis that had intradialytic complications such as hypotension, muscle cramp, nausea, vomiting and headache were studied. These patients were studied in four 45 day periods, beginning with no treatment (step 1), receiving vitamin E (200 IU/d) (step 2), receiving L-carnitine (500 mg/d) (step 3) and their combination (step 4). Intradialytic complications were recorded in each step and compared between treatments.

RESULTS

All three treatments significantly reduced frequency of muscle cramps in comparison to baseline values. Vitamin E alone and in combination with L-carnitine reduced the frequency of muscle cramps more effectively. Hypotension was significantly lower in combination therapy in comparison to baseline values and vitamin E treatment.

CONCLUSIONS

Vitamin E and L-carnitine both have comparative effects on intradialytic complications. As the combination use of vitamin E and L-carnitine could more effectively reduce the intradialytic complications, it is recommended for daily use in hemodialysis patients.

Carnitine supplementation improves cardiac strain rate in children on chronic hemodialysis

BACKGROUND

Carnitine plays a key role in energy production in the myocardium. Carnitine deficiency commonly occurs in patients on chronic hemodialysis (HD) and may contribute to cardiomyopathy.

METHODS

Carnitine levels and cardiac function of nine children on HD were assessed before and after 6 months of intravenous levocarnitine supplementation. Standard echocardiographic (ECHO) measures of left ventricular (LV) function as well as strain and strain rate analysis using novel speckle-tracking echocardiography were performed and the results compared to those of a control group of children on chronic HD.

RESULTS

Following carnitine supplementation, total (49.0 ± 1.67 vs. 298.0 ± 31.8 μmol/L) and free carnitine (29.0 ± 1.20 vs. 180.4 ± 19.2 μmol/L) increased (p < 0.0001), and the acyl:free (A:F) carnitine ratio improved (0.73 ± 0.04 vs. 0.65 ± 0.05; p = 0.02). There were no changes in standard ECHO measures of LV function, including end diastolic dimension, mass index, ejection fraction, and fractional shortening. There was significant (p = 0.017) improvement in the longitudinal strain rate (-1.48 ± 0.11 vs -1.91 ± 0.12) after carnitine supplementation in the study group. No improvements in LV function, strain, or strain rate occurred in controls.

CONCLUSIONS

Levocarnitine supplementation improved carnitine levels, the A:F ratio, and longitudinal strain rate in children on HD.

Use of agents stimulating erythropoiesis in digestive diseases

Anemia is the most common complication of inflammatory bowel disease (IBD). Control and inadequate treatment leads to a worse quality of life and increased morbidity and hospitalization. Blood loss, and to a lesser extent, malabsorption of iron are the main causes of iron deficiency in IBD. There is also a variable component of anemia related to chronic inflammation. The anemia of chronic renal failure has been treated for many years with recombinant human erythropoietin (rHuEPO), which significantly improves quality of life and survival. Subsequently, rHuEPO has been used progressively in other conditions that occur with anemia of chronic processes such as cancer, rheumatoid arthritis or IBD, and anemia associated with the treatment of hepatitis C virus. Erythropoietic agents complete the range of available therapeutic options for treatment of anemia associated with IBD, which begins by treating the basis of the inflammatory disease, along with intravenous iron therapy as first choice. In cases of resistance to treatment with iron, combined therapy with erythropoietic agents aims to achieve near-normal levels of hemoglobin/hematocrit (11-12 g/dL). New formulations of intravenous iron (iron carboxymaltose) and the new generation of erythropoietic agents (darbepoetin and continuous erythropoietin receptor activator) will allow better dosing with the same efficacy and safety.

Endogenous plasma carnitine pool composition and response to erythropoietin treatment in chronic haemodialysis patients

BACKGROUND

Anaemia is a common complication associated with haemodialysis and is usually managed by treatment with recombinant human erythropoietin (rHuEPO). However, many patients remain hyporesponsive to rHuEPO treatment despite adequate iron therapy. The effect of L-carnitine administration on rHuEPO dose and/or haematocrit in haemodialysis patients has been previously reported with equivocal results. This study examined the relationship between endogenous carnitine pool composition and rHuEPO requirements in long-term haemodialysis patients.

METHODS

Pre-dialysis blood samples were collected from 87 patients and analysed for plasma L-carnitine and individual acylcarnitine levels by LCMS/MS. As an indication of rHuEPO responsiveness, erythropoietin resistance index (ERI) was calculated as rHuEPO dose/kg/week normalized for haemoglobin levels.

RESULTS

A significant negative correlation between L-carnitine levels and ERI was found (P = 0.0421). All patients categorized as high ERI (>0.02 microg/kg/week/gHb) exhibited subnormal L-carnitine levels (<30 microM); conversely, patients with normal L-carnitine levels (>30 microM) displayed low ERI values (<0.02 microg/kg/week/gHb). More importantly, the ratio of non-acetyl acylcarnitines/total carnitine was significantly positively correlated with ERI (P = 0.0062).

CONCLUSIONS

These data illustrate the relationship between carnitine levels and response to rHuEPO treatment in haemodialysis patients, in particular, the importance of the proportion of long-chain acylcarnitines within the plasma carnitine pool. This proportion may be more indicative of the response to L-carnitine supplementation than absolute L-carnitine levels alone.

Inflammatory syndrome in patients on hemodialysis

Mortality is markedly elevated in hemodialysis (HD) patients. Between 30 and 50% of prevalent patients have elevated serum levels of inflammatory markers such as C-reactive protein and IL-6. The presence of inflammation, chronic or episodic, has been found to be associated with increased mortality risk. The causes of inflammation are multifactorial and include patient-related factors, such as underlying disease, comorbidity, oxidative stress, infections, obesity, and genetic or immunologic factors, or on the other side, HD-related factors, mainly depending on the membrane biocompatibility and dialysate quality. The adequate knowledge of these causes and their prevention or treatment if possible may contribute to improving the inflammatory state of patients who are on HD and possibly their mortality.

Effect of L-carnitine on erythroid colony formation in mouse bone marrow cells

BACKGROUND

l-Carnitine can alleviate uraemic anaemia in haemodialysis patients by improving erythrocyte membrane functions or erythropoiesis, which are depressed under uraemic conditions. l-Carnitine and palmitoyl-l-carnitine were reported to increase the formation of colony-forming unit-erythroid (CFU-E) colonies in cultures of fetal mouse liver cells, an effect that depended on the concentration of palmitoyl-l-carnitine but not of l-carnitine. In this study, we investigated l-carnitine's effect on CFU-E colony formation in cell cultures of mouse bone marrow cells.

METHODS

Bone marrow from normal female mice was placed in 35 mm culture dishes containing a medium composed of methylcellulose and various nutrients. The dishes were incubated for 48 h, and the colonies of erythroblasts, which were differentiated from CFU-E, consisting of >/=8 cells, were counted in each dish using an inverted microscope.

RESULTS

The numbers of CFU-E colonies correlated well with both the initial numbers of bone marrow cells and concentrations of recombinant human erythropoietin (rhEPO) in the methylcellulose medium. In the presence of 0.5 or 1.0 IU/ml of rhEPO, l-carnitine at concentrations of 200 and 400 micromol/l significantly enhanced CFU-E colony formation (P<0.001).

CONCLUSION

l-Carnitine significantly increased the number of CFU-E colonies in mouse bone marrow cell cultures. This finding suggests that l-carnitine stimulates erythropoiesis, partially accounting for its mitigating effect on renal anaemia.

Carnitine and hemodialysis

Carnitine, gamma-trimethyl-beta-hydroxybutyrobetaine, is a small molecule widely present in all cells from prokaryotic to eukaryotic. It is an important element in the beta-oxidation of fatty acids. A lack of carnitine in hemodialysis patients is caused by insufficient carnitine synthesis and particularly by the loss through dialytic membranes, leading in some patients to carnitine depletion with a relative increase of esterified forms. The authors found a decrease in plasma-triglyceride and increase of high-density lipoprotein cholesterol (HDL-Chol) in dialysis patients during carnitine treatment. Many studies have shown that L-carnitine supplementation leads to improvements in several complications seen in uremic patients, including cardiac complications, impaired exercise and functional capacities, muscle symptoms, increased symptomatic intradialytic hypotension, and erythropoietin-resistant anemia, normalizing the reduced carnitine palmitoyl transferase activity in red cells. In addition, carnitine supplementation may improve protein metabolism and insulin resistance. Recently, carnitine supplementation has been approved by the US Food and Drug Administration not only for the treatment, but also for the prevention of carnitine depletion in dialysis patients. Regular carnitine supplementation in hemodialysis patients can improve their lipid metabolism, protein nutrition, antioxidant status, and anemia requiring large doses of erythropoietin, It also may reduce the incidence of intradialytic muscle cramps, hypotension, asthenia, muscle weakness, and cardiomyopathy.

History of L-carnitine: implications for renal disease

L-carnitine (LC) plays an essential metabolic role that consists in transferring the long chain fatty acids (LCFAs) through the mitochondrial barrier, thus allowing their energy-yielding oxidation. Other functions of LC are protection of membrane structures, stabilizing a physiologic coenzyme-A (CoA)-sulfate hydrate/acetyl-CoA ratio, and reduction of lactate production. On the other hand, numerous observations have stressed the carnitine ability of influencing, in several ways, the control mechanisms of the vital cell cycle. Much evidence suggests that apoptosis activated by palmitate or stearate addition to cultured cells is correlated with de novo ceramide synthesis. Investigations in vitro strongly support that LC is able to inhibit the death planned, most likely by preventing sphingomyelin breakdown and consequent ceramide synthesis; this effect seems to be specific for acidic sphingomyelinase. The reduction of ceramide generation and the increase in the serum levels of insulin-like growth factor (IGF)-1, could represent 2 important mechanisms underlying the observed antiapoptotic effects of acetyl-LC. Primary carnitine deficiency is an uncommon inherited disorder, related to functional anomalies in a specific organic cation/carnitine transporter (hOCTN2). These conditions have been classified as either systemic or myopathic. Secondary forms also are recognized. These are present in patients with renal tubular disorders, in which excretion of carnitine may be excessive, and in patients on hemodialysis. A lack of carnitine in hemodialysis patients is caused by insufficient carnitine synthesis and particularly by the loss through dialytic membranes, leading, in some patients, to carnitine depletion with a relative increase in esterified forms. Many studies have shown that LC supplementation leads to improvements in several complications seen in uremic patients, including cardiac complications, impaired exercise and functional capacities, muscle symptoms, increased symptomatic intradialytic hypotension, and erythropoietin-resistant anemia, normalizing the reduced carnitine palmitoyl transferase activity in red cells.