Dileep S. Sachan

Decreasing oxidative stress with choline and carnitine in women.

Objective: Fatty acid oxidation is predominantly a mitochondrial event, which is enhanced by dietary choline and carnitine supplementation resulting in extra reactive oxygen species (ROS) load. The objective was to assess oxidative stress level by thiobarbituric acid reactive substances [TBARS] in choline and carnitine supplemented healthy women before and after mild exercise. Methods: Nineteen free-living women completed the placebo control study in which choline and/or L-carnitine was orally taken for 21 days. Anthropometric measurements, dietary recall, exercise routine and blood samples were analyzed to determine body composition, nutrients intake, distance walked and biochemical markers related to oxidative stress. Results: TBARS were significantly lower in the groups supplemented with choline, carnitine or both and the mild exercise (walking) was not a deterrent in this effect of the supplements. Serum vitamin A and E concentrations were higher in the supplemented groups even though the consumption of these nutrients was not different among the groups. Conclusion: Choline and carnitine supplementation lowers lipid peroxidation, and promotes conservation of retinol and α-tocopherol in free-living women.

Alterations of serum and urinary carnitine profiles in cancer patients: hypothesis of possible significance.

The present study examined the serum and urinary carnitine concentrations of 21 cancer patients with metastatic disease and 13 healthy age-matched controls by taking three consecutive samples during an 8-week period. The serum concentrations of all fractions of carnitine were significantly lower in the female cancer patients than in the female controls. The concentrations of urinary carnitine fractions were relatively higher in the total cancer population; however, only acid-insoluble acylcarnitine (AIAC) was statistically significant. The renal clearance of acid-soluble acylcarnitine (ASAC) and AIAC was significantly greater in cancer subjects than in controls. Significant inverse relationships were established between the ASAC and AIAC clearances and their respective serum concentrations. The renal tubular reabsorption of AIAC was significantly less in cancer patients than in control subjects as indicated by the fractional excretion of carnitine. The increased clearance of acylcarnitine and excretion of large amounts of AIAC are proposed to be a response to chemotherapy and represent a loss of energy to the cancer patient.

Anesthetics and cardiocentesis increase urinary carnitine excretion in rats and guinea pigs

Our interest in carnitine homeostasis lead us to determine effects of several commonly used anesthetics and blood sampling procedures on serum and urinary carnitine concentrations. Serum and urine samples were collected from male rats and guinea pigs prior to and after anesthesia with and without cardiocentesis and assayed for carnitine and acylcarnitine. Methoxyflurane alone increased urinary carnitine excretion in guinea pigs but not in rats. Methoxyflurane plus cardiocentesis increased urinary carnitine and acylcarnitine in both species, and isoflurane mimicked methoxyflurane in rats. Cardiocentesis with phenobarbital or pentobarbital increased carnitine and acylcarnitine in serum but not in urine. Ketamine plus acepromazine increased total carnitine only in the serum of rats. A combination of ketamine and xylazine increased serum carnitine and urinary acylcarnitine. It is concluded that anesthesia and cardiocentesis increased serum and urinary carnitine and acylcarnitines differently depending on the species and the anesthetic administered.

Modulation of drug metabolism by food restriction in male rats.

Abstract Forty-five percent food restriction for 28 days in male rats caused a significant decrease in hexobarbital sleeping time which was inversely related to hepatic cytochrome P-450 content. These changes corroborated well with enhanced in vitro activity of hepatic microsomal aniline hydroxylase, p-chloromethylaniline-N-demethylase and p-nitrobenzoate reductase and concomitant increases in cytosolic G-6-P + 6-PG dehydrogenase and malic enzyme activities. Thus food restriction, unlike starvation, enhances drug metabolism and related enzymatic activity.

Choline supplementation increases tissue concentrations of carnitine and lowers body fat in guinea pigs

Abstract It has been documented that choline supplementation results in urinary conservation of carnitine in both humans and guinea pigs. This conservation in guinea pigs is associated with increased concentrations of carnitine in skeletal muscle for which no functional consequences have been reported. The objective of this study was to evaluate changes in fat metabolism and body composition as a consequence of the increased tissue carnitine in choline-supplemented guinea pigs. Guinea pigs were given free access to commercial diet without or with 3 g choline/kg diet. Using indirect calorimetry, the respiratory exchange ratios (RER) of the animals were determined under normal, exercise, and unfed conditions. There were no differences in RER between supplemented and nonsupplemented groups under any of the conditions. The RER data lead to the conclusion that choline–carnitine did not promote oxidation of fat over carbohydrates for energy. However, proximate analysis of carcass revealed significantly lower total body fat and higher body proteins in the choline-supplemented animals compared with the nonsupplemented animals. These apparently contradictory results are explained by the hypothesis that the acetates generated by the β-oxidation of fatty acids are transferred to carnitine and not oxidized to carbon dioxide, resulting in little or no shift in RER.

Acetylcarnitine-mediated inhibition of ethanol oxidation in hepatocytes

Carnitine-mediated prevention of ethanol-induced hepatic steatosis is related to the attenuation of ethanol metabolism by carnitine in the intact rat. Although carnitine retards ethanol oxidation in the intact animal, the in vitro activities of ethanol-metabolizing enzymes remain unaltered. Therefore, hepatocytes were targeted to understand the mechanism of carnitine effect on ethanol metabolism. Rat hepatocytes were isolated by a collagenase-perfusion technique and incubated in albumin-containing medium with ethanol in the presence or absence of added carnitine or related compounds. Ethanol oxidation was determined by the loss of ethanol as well as by the products formed. The rate of ethanol oxidation in the presence of carnitine was one-half the rate in the absence of carnitine (14 vs. 25 nmol.min-1.million-1 cells). It took 100 times the concentration of carnitine to equal the maximal inhibition produced by acetylcarnitine and the effect of acetylcarnitine was without a lag time. It is concluded that acetylcarnitine is the mediator of carnitine inhibition of ethanol oxidation.

Plasma Carnitine Alterations in Premature Infants Receiving Various Nutritional Regimes

Plasma carnitine, carnitine esters, and triglyceride concentrations were determined in 36 appropriate-forgestational-age (AGA) infants at various stages of prematurity throughout hospitalization to determine the effect of a carnitine-free and carnitine-containing diet on plasma carnitine and triglyceride concentrations. The infants were entered into one of three experimental groups based on birth weight: group I less than 1.0 kg; group II 1.0-1.51 kg; and group III 1.52-2.5 kg. Throughout the study subjects were placed on appropriate nutritional regimes which included hyperalimentation (HA), intravenous (iv) fat emulsion (Intralipid), Portagen, Enfamil-24 Premature Formula, Enfamil-20, and breastmilk. Blood samples were drawn from each infant at birth, days 1-5,7 then weekly, also before and after each nutritional intervention to determine carnitine and triglyceride concentrations. Results showed that plasma total carnitine and nonesterified carnitine decreased in all groups when the infants were maintained on a carnitine-free diet (HA, Intralipid, Portagen). In general, the carnitine levels continued to decrease until a carnitine-containing diet was initiated. Once a carnitine-containing diet was begun, plasma total carnitine (TC) and nonesterified carnitine (NEC) levels increased at fairly similar rates in all groups. However, an inverse relationship between carnitine and triglyceride (TG) concentrations were not seen in these infants. This would indicate that most premature infants require exogenous carnitine to maintain the plasma concentration of carnitine. However, a decreased concentration of plasma carnitine was not correlated with an elevated TG level under the conditions of this study.

Effects of supplementary levels of L-carnitine on blood and urinary carnitines and on the portal-systemic blood-ethanol concentrations in the rat

Abstract Male Sprague-Dawley rats of about 300 g body weight were fed ground Rodent Chow or the same mixed with 0.0025, 0.005, 0.0075, or 0.01 (wt/wt) L -carnitine for 10 days. Changes in blood and urinary carnitines were monitored on days 0, 1, 3, 5, 7, and 10 of feeding carnitine supplemented (CS) diets. Changes in the portal and systemic blood-ethanol were monitored on day 11 following an intraduodenal dose of ethanol. Blood and urinary carnitines peaked after days 3 and 5, respectively, following the 0.005 level of carnitine supplementation which was found adequate. The urinary carnitine fractions followed the pattern of blood carnitines and there were strong positive correlation (r = 0.83) between blood and urinary total and nonesterified carnitines. While rates of ethanol appearance in the portal blood remained essentially unaltered, the systemic blood ethanol concentrations were significantly elevated in the carnitine supplemented rats during the initial 30 minutes. It is concluded that feeding of 0.005 CS diet for three days was adequate to attain peak blood carnitine concentrations and that carnitine retarded ethanol metabolism without altering the rates of ethanol absorption from the small intestine.

Attenuation of ethanol metabolism by supplementary carnitine in rats

The purpose of this study was to examine the effect of supplementary D,L-carnitine on blood-ethanol levels and ascertain if the effect was a result of altered absorption or metabolism of ethanol. Mature male Sprague-Dawley rats were fed Purina Rat Chow as such or supplemented with various levels of D,L-carnitine. First it was established that supplementing carnitine at 1% (w/w) level produced steady state concentrations of carnitine in blood after 3 days of feeding. When a single dose of ethanol was given orally after 5 days of carnitine supplementation, the blood levels of ethanol remained significantly elevated for 2-8 hours in the carnitine supplemented animals. Time course of blood-ethanol concentrations revealed that carnitine did not affect the rates of ethanol absorption and therefore, the effect must be due to the attenuation of ethanol clearance from the blood.

Opposite effects of dietary saturated and unsaturated fatty acids on ethanol-pharmacokinetics, triglycerides and carnitines

OBJECTIVE The objective of this study was to determine the effects of saturated fatty acid (SFA) and unsaturated fatty acid (UFA) diets on ethanol pharmacokinetics. Hepatic ADH and plasma carnitines were also evaluated as possible indicators of the mechanism involved. METHODS Sprague-Dawley male rats were fed modified AIN76 diets containing 10% coconut oil (SFA) or corn oil (UFA) for 120 days. A single dose (3 g/kg bw) of ethanol (13% solution) was orally administered using a gastric canula on day 30, 90, 105 and 120. Tail vein blood samples were collected at various intervals following ethanol dose and were analyzed for blood-ethanol concentration (BEC). In an analogous trial rats were given these diets for 70 days and blood samples were collected on day 35 and 63 for triglycerides, cholesterol and carnitine determination. The animals were killed on day 70 to collect liver for ADH determination. RESULTS Compared to the UFA group, the SFA group exhibited significantly higher BEC, larger area under the curve, longer half-life of ethanol, and lower rates of ethanol elimination. Plasma carnitines were also higher in the SFA vs UFA group. However, hepatic ADH activity was not different between the groups. CONCLUSION Dietary SFA protects liver from alcohol injury by retarding ethanol metabolism, and carnitine may be involved.