Carnitine Administration Research Articles

No replenishment of carnitine from trimethyllysine during pivalate-induced carnitine loss in humans

Pivaloylcarnitine formation from exogenous carnitine and from carnitine precursor 6-N-trimethyllysine was investigated in two groups of pivampicillin treated subjects. In the first group, medication of pivampicilin led to the formation of and urinary excretion of pivaloylcarnitine. Oral L-carnitine supplementation, introduced after the third day of treatment, caused 2 fold urinary excretion of carnitine esters. For this group, the plasma levels and urinary output of butyrobetaine also decreased on the third day of pivampicillin treatment, but it normalized after carnitine administration. In contrast, urinary output of the carnitine precursor, trimethyllysine did not change during the study period. For the second group, oral trimethyllysine supplementation was started on the 4th day of pivampicillin treatment. Administration of trimethyllysine had no effect on the urinary output of carnitine esters, although the urinary excretion of it increased from approximately 25 to 450 μmol/day. Plasma levels and urinary output of butyrobetaine decreased during the pivampicillin treatment and administration of trimethyllysine did not restore the levels. Administration of trimethyllysine produced a large increase in urinary trimethyllysine output, but it did not affect the fast atom bombardment mass spectrometry signal intensity of other carnitine precursors. The urinary metabolite profile shows, that the conversion process of trimethyllysine to hydroxy-trimethyllysine represent and obstacle in butyrobetaine and carnitine biosynthesis in humans in vivo. Because the administered trimethyllysine was not converted to carnitine or carnitine precursors to any significant extent, its nutritional value with respect to the replenishment of carnitine reserves is questionable.

Effects of carnitine on preconditioned latissimus dorsi muscle at different burst frequencies.

Exercise and electrical stimulation may result in a decrease in carnitine levels associated with preconditioned latissimus dorsi muscles. Therefore, the effects of exogenous carnitine were studied in a model of latissimus dorsi muscle contraction. Twelve dogs were studied. Under anesthesia, the latissimus dorsi was placed around an implantable mock circulation system. The muscle was made fatigue-resistant with the aid of chronic low-frequency electrical stimulation. Six animals received carnitine 0.15 mmol/kg; the other six served as control. The muscles were stimulated with 20, 43, and 85 Hz pulse training. During the 90-minute stimulation period, the pressure that developed in the mock circulation was measured at 15 minute intervals. The changes in ATP and lactate levels were measured every 30 minutes. Stimulations at 20 and 43 Hz did not result in any change in pressure or metabolic data over the course of 90 minutes of stimulation. When the 85 Hz burst was applied, ATP levels decreased, while lactate levels increased, with an associated drop in pressure in the control group. ATP and lactate levels were, respectively, 13.8 +/- 1.4 mumol/g and 15.0 +/- 4.0 mumol/g in the carnitine group and 10.3 +/- 1.1 mumol/g and 23.0 +/- 3.0 mumol/g in the control group at the end of 90 minutes (p < 0.06). The pressure at the same time interval was 74 +/- 4 mmHg in the control group, and 85 +/- 3 mmHg in the carnitine group (p < 0.05). In this study, we demonstrated that carnitine administration enhances muscle performance in terms of metabolic and pressure changes during high-frequency electrical stimulation at 85 Hz.

Altered Expression of Atrial Natriuretic Peptide and Contractile Protein Genes in Hypertrophied Ventricle of JVS Mice with Systemic Carnitine Deficiency

To characterize cardiac hypertrophy in juvenile visceral steatosis (JVS) mice with systemic carnitine deficiency, we investigated how the hypertrophy develops and whether it is associated with altered expression of any specific genes, especially atrial natriuretic peptide (ANP) and contractile protein genes, in the hypertrophied ventricle. Cardiac hypertrophy in JVS mice became apparent at 10 days after birth and progressed during development. The hypertrophy was observed in the ventricles but not in the atria. ANP mRNA was more intensively expressed in JVS ventricles than in control even at 5 days. Carnitine administration ameliorated the cardiac hypertrophy and suppressed the augmentation of ANP mRNA in the ventricles. Isoform change of expression ofα-actin genes from cardiac to skeletal was seen in the ventricles of JVS mice at 2 weeks. There was no difference in the ratio ofβ-myosin heavy chain mRNA toα-myosin heavy chain mRNA between control and JVS mice at 5 days, but at 2 weeks the ratio was significantly lower in JVS mice than in control. These results suggest that the molecular characteristics of cardiac hypertrophy caused by carnitine deficiency are different from those of cardiac hypertrophy caused by aortic constriction.

The effect of dietary carnitine supplementation on growth of red sea bream ( Pagrus major) fingerlings at two levels of dietary lysine

The effect of dietary carnitine supplementation (2 g kg −1 diet) on growth, proximate, neutral lipid and fatty acid composition of liver and muscle of red sea bream fingerlings at two levels of dietary lysine (10 and 14 g kg −1 diet, respectively) was investigated. Carnitine increased red sea bream growth fed a 14 g lysine kg −1 diet ( P < 0.05) but did not cause any effect on growth in fish fed the 10 g lysine kg −1 diet. A clear lysine sparing effect of carnitine in red sea bream was not observed. Carnitine did not reduce crude lipid levels in white muscle and liver of fish. Fatty acid composition of total lipids in liver showed reduced values for eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and total long-chain fatty acids with 20 to 24 carbon atoms (ΣC 20–24) in fish receiving carnitine supplemented diets indicating an increased utilization of the above fatty acids. Free carnitine and acid-soluble carnitine in muscle increased two-fold after carnitine administration.

METABOLIC AND RENAL EFFECTS OF LAEVO-CARNITINE AND PROPIONYL-CARNITINE IN RATS WITH SUBTOTAL NEPHRECTOMY

The renal and metabolic effects of chronic carnitine administration were evaluated in the early stages of experimentally-induced renal failure. Laevo-carnitine (n=5), Propionyl-carnitine (n=5) both at 200mgkg−1of body weight, or vehicle (physiological saline solution, 0.4mlkg−1body weight,n=5) were administered daily for 3 days prior to 2/3 nephrectomy and for 25 days thereafter, by intraperitoneal route. At the end of the experiment, no significant differences were found in systolic blood pressure and heart rate among groups. During the 25 days after nephrectomy, body weight increased by 71±13g in the control group and by 50±26g and 42±9g in Laevo-carnitine and Propionyl-carnitine groups, respectively (P<0.05vscontrol for both comparisons). Urinary sodium excretion was increased in carnitine-treated rats (Laevo-carnitine: from 1.03±0.3 to 1.36±0.3mEq day−1, Propionyl-carnitine: from 1.2±0.2 to 1.66±0.2mEq day−1,P<0.05 for both comparisons), but not in those given vehicle. Twenty-five days after nephrectomy, plasma creatinine was lower in carnitine-treated rats (Laevo-carnitine: 0.98±0.12mgdl−1, Propionyl-carnitine: 1.06±0.15, vehicle: 1.52±0.09,P<0.05vscontrol for both comparisons). Plasma triglycerides and VLDL were decreased by nephrectomy and this effect was prevented by carnitine treatment. The data indicate that the carnitine blunts the increase in plasma creatinine that occurs early after partial nephrectomy and normalizes the plasma lipoprotein pattern. Thus, carnitine might protect against the development of renal failure in this experimental model.

Disordered expression of glycolytic and gluconeogenic liver enzymes of juvenile visceral steatosis mice with systemic carnitine deficiency

A quantitative study of the effect of carnitine deficiency on expression of glycolytic and gluconeogenic enzymes was performed using juvenile visceral steatosis mice which are systemically deficient in carnitine. The amounts of glucokinase and L-type pyruvate kinase mRNA were reduced in homozygotes, compared to heterozygotes and normal controls at 2 and 8 weeks. Liver-type phosphofructokinase, however, did not differ significantly. The abundance of fructose 1,6-bisphosphatase mRNA was unchanged at 2 and 8 weeks. The level of phosphoenolpyruvate carboxykinase mRNA was increased slightly at 2 weeks, but not at 8 weeks. A part of these changes could not be explained by the plasma glucose or insulin level. Carnitine administration restored the mRNA of these enzymes to normal levels. These results suggest that carnitine deficiency affects the expression of these liver enzymes.

Altered expression of carnitine palmitoyltransferase II in liver, muscle, and heart of mouse strain with juvenile visceral steatosis

We conducted a quantitative study of the effect of carnitine deficiency on the mRNA level of carnitine palmitoyltransferase II in the liver, muscle and heart of mice with juvenile visceral steatosis, a strain that is systemically deficient in carnitine. The amount of carnitine palmitoyltransferase II mRNA was increased in liver and muscle of homoxygotes, as compared with heterozygotes and normal controls, at 2, 4, and 8 wk of age. The mRNA levels of this enzyme were normalized after carnitine administration. The mRNA level of carnitine palmitoyltransferase II in the heart was increased only at 8 wk, and was not affected by carnitine administration. These results suggest that carnitine displays some effect on the mRNA level of the carnitine palmitoyltransferase II gene in liver and muscle, probably through fatty acid metabolic change.

Effect of carnitine on decrease of branched chain amino acids and glutamine in serum of septic rats.

Blood concentrations of branched chain amino acids (BCAA; leucine, isoleucine, and valine) and glutamine (Gln) decrease markedly in sepsis. We investigated the effect of carnitine on serum concentrations of BCAA and Gln in fasted septic rats. Rats were made septic by cecal ligation and puncture. They developed extremely high blood concentrations of endotoxin, and serum concentrations of BCAA and Gln were markedly decreased 2 d after the operation. When L-carnitine was administered subcutaneously to the rats at 500 mg/kg body weight every 12 h for 2 d starting at the operation, no decrease in the serum concentrations of BCAA and Gln was observed. This indicates that the administration of carnitine can prevent the decrease of serum concentrations of BCAA and Gln in septic animals.

Letters to the Editor

The report of a study of 47 children by Freeman et al1 indicated administration of carnitine did not significantly improve symptoms associated with the anticonvulsant medications valproic acid and carbamazepine. Further study has been recommended to validate the clinical impression of some workers that therapeutic carnitine may be beneficial for some patients with low carnitine levels.2 Recent experience at a large residential training and treatment center for the mentally retarded provides further pertinent information. At Southside Virginia Training Center for the mentally retarded in Petersburg, Virginia, 40% of the residents received anticonvulsant medication for epilepsy.

Letters to the Editor

We read with interest the report of Drs Hunt and Pellock on screening a population of institutionalized patients for carnitine deficiency. There did not appear to be any substantial correlation between the carnitine levels and the patient's function, handicap, or the ingestion of anticonvulsants. This population could be useful for a blinded test of the reported beneficial effects of carnitine administration. The letter from Sigma-Tau Pharmaceuticals, manufacturers of Carnitor, is, I believe, an intentionally misleading and disingenuous extension of their advertising campaign of which my quote is the opening sentence.

Responses of Dairy Cows During Early Lactation to Ruminal or Abomasal Administration of L-Carnitine

Six multiparous Holstein cows were used in a replicated Latin square to investigate the effects of carnitine administration into the rumen or abomasum. Treatments were 1) control, 2) twice daily ruminal administration of carnitine, and 3) continuous abomasal infusion of carnitine. Cows not receiving abomasal carnitine were infused continuously with an equal volume of water. Carnitine dosage was constant for both treatments (226 mg/kg of DMI; ca. 6 g/d). The diet fed to all cows contained 3% added fat. Carnitine concentrations in plasma and liver increased when carnitine was administered into either the rumen or abomasum, indicating that both sites of administration were equally effective at increasing carnitine concentrations in tissue. Milk yield, milk composition, and DMI were unaffected by carnitine supplementation, except for increased SNF content. Apparent digestibilities of lipid, energy, and total fatty acids increased with carnitine administration at either site. The concentration of VFA in ruminal fluid tended to increase with ruminal carnitine, and the percentage of propionate increased when carnitine was administered at either site. Retained N tended to increase when carnitine was administered, primarily because of greater retained N when carnitine was administered ruminally. Excretion of carnitine in milk and urine increased when carnitine was administered at either site. Carnitine supplementation increased concentrations of carnitine in plasma and liver and improved lipid digestibility.

Effects of l-carnitine administration on left ventricular remodeling after acute anterior myocardial infarction: the l-Carnitine Ecocardiografia Digitalizzata Infarto Miocardico (CEDIM) trial

Objectives. This study was performed to evaluate the effects of l-carnitine administration on long-term left ventricular dilation in patients with acute anterior myocardial infarction.Background. Carnitine is a physiologic compound that performs an essential role in myocardial energy production at the mitochondrial level. Myocardial carnitine deprivation occurs during ischemia, acute myocardial infarction and cardiac failure. Experimental studies have suggested that exogenous carnitine administration during these events has a beneficial effect on function.Methods. The l-Carnitine Ecocardiografia Digitalizzata Infarto Miocardico (CEDIM) trial was a randomized, double-blind, placebo-controlled, multicenter trial in which 472 patients with a first acute myocardial infarction and high quality two-dimensional echocardiograms received either placebo (239 patients) or l-carnitine (233 patients) within 24 h of onset of chest pain. Placebo or l-carnitine was given at a dose of 9 g/day intravenously for the first 5 days and then 6 g/day orally for the next 12 months. Left ventricular volumes and ejection fraction were evaluated on admission, at discharge from hospital and at 3, 6 and 12 months after acute myocardial infarction.Results. A significant attenuation of left ventricular dilation in the first year after acute myocardial infarction was observed in patients treated with l-carnitine compared with those receiving placebo. The percent increase in both end-diastolic and endsystolic volumes from admission to 3-, 6- and 12-mouth evaluation was significantly reduced in the l-carnitine group. No significant differences were observed in left ventricular ejection fraction changes over time in the two groups. Although not designed to demonstrate differences in clinical end points, the combined incidence of death and congestive heart failure after discharge was 14 (6%) in the l-carnitine treatment group versus 23 (9.6%) in the placebo group (p = NS). Incidence of ischemic events during follow-up was similar in the two groups of patients.Conclusions. l-Carnitine treatment initiated early after acute myocardial infarction and continued for 12 months can attenuate left ventricular dilation during the first year after an acute myocardial infarction, resulting in smaller left ventricular volumes at 3, 6 and 12 months after the emergent event.

Pharmacokinetic considerations for the therapeutic use of carnitine in hemodialysis patients

Clinical observations have suggested that carnitine supplementation may be beneficial to a subset of patients receiving chronic hemodialysis. In the absence of definitive clinical trials, the clinician must decide for an individual patient whether a trial of carnitine therapy is justified. The institution of carnitine therapy is further complicated by the availability of oral and intravenous dosing forms and by the compound's complex pharmacokinetics. The oral systemic bioavailability of carnitine in normal subjects is 5% to 16%, with peak plasma carnitine concentrations reached 2 to 6 hours after dosing. Carnitine is initially distributed into extracellular water and then more slowly enters tissue compartments with complex kinetics. Elimination of carnitine is through the urine or dialysate. Intravenous carnitine administration results in large peak plasma concentrations and assures systemic bioavailability. Orally administered carnitine has been reported to have clinical efficacy in hemodialysis patients in doses of 2 to 4 g per day in divided doses. Intravenous carnitine has also been widely used in clinical trials in attempts to demonstrate efficacy in the hemodialysis population; however, the available data do not establish the superiority of the intravenous formulation over the oral form. Intravenous carnitine may have theoretical advantages in initiating treatment when high peak concentrations are required to facilitate carnitine reaching nonhepatic tissue sites or when oral carnitine therapy is not feasible due to poor tolerance or compliance. Although comparative trials are lacking, it is probable that oral therapy can be used for long-term maintenance, regardless of which formulation was used to initiate therapy. The decision to use carnitine therapy, as well as the dose and route of administration, requires individualization based on the clinical status of the patient and the goals of therapy.

Effects of parenteral L-carnitine supplementation on fat metabolism and nutrition in premature neonates

The effects of parenteral L-carnitine supplementation on fat metabolism, nutrient intake, and plasma and erythrocyte carnitine concentrations were studied in 43 very low birth weight infants. Infants were randomly assigned to control or carnitine-supplemented (50 μmol/kg per day) groups within two weight categories: group 1, 750 to 1000 gm, and group 2, 1001 to 1500 gm. Plasma total, free, and acyl carnitine levels, erythrocyte carnitine levels, serum β-hydroxybutyrate and triglyceride levels, and total fat intake were monitored weekly until 50% of total caloric intake was met enterally. Neonates receiving carnitine had higher plasma carnitine levels than control groups (total carnitine: group 1, 75.2 ± 22.9 vs 9.6 ± 2.7 mmol/ml; group 2, 61.6 ± 31.2 vs 13.0 ± 9.2 nmol/ml). Levels of β-OH-butyrate decreased from baseline in control neonates (group 1, 0.12 ± 0.06 to 0.03 ± 0.02 mmol/L; group 2, 0.11 ± 0.03 to 0.05 ± 0.02 mmol/L); they remained unchanged in supplemented groups. Thus ketogenesis appeared less impaired in infants receiving supplements. Supplemented group 2 tolerated more fat than control group 2; triglyceride levels remained acceptable in all groups. Carnitine group 2 had greater weight gain than control group 2 during the first 2 weeks of life. We conclude that very low birth weight infants requiring prolonged parenteral nutrition have carnitine deficiency with impaired ketogenesis. Parenteral administration of carnitine appears to alleviate this metabolic disturbance. (J P EDIATR 1995;126:287-92)

159 CARNITINE DEPENDENT CHANGES OF METABOLIC FUEL CONSUMPTION IN CHRONIC VALPROATE TREATMENT

Composition of energy metabolism was determined in children receiving chronic valproate treatment with indirect calorimetry. In eight of ten randomly selected subjects the resting respiratory quotient (RQ) increased as compared with age and sex matched controls (0.91±0.01 vs 0.87±0.01). A shift was observed in the metabolic fuel consumption, decrease was found in fats oxidised (0.68±0.23 vs 1.18±0.18 g/kg/day) and the utilisation of carbohydrates increased (5.31±0.79 vs 3.81±0.39 g/kg/day), with no significant change of the urinary output of nitrogen compounds. The resting total energy expenditure was not affected by the treatment. The children showing altered energy consumption pattern received carnitine supplementation for a month. After the carnitine administration the RQ value decreased (0.87±0.02) and an increase was in the oxidation of fats (1.42±0.25), the consumption of carbohydrates decreased (3.87±0.79). The resting energy consumption was not affected by the treatment. The results show, that carnitine depletion, which is a known adverse effect of valproic acid administration, may result in inhibited fatty acid oxidation leading to a shift from fats to carbohydrates in composition of substrates utilised.

Abnormal gene expression and regulation in the liver of jvs mice with systemic carnitine deficiency

Carnitine-deficient jvs mice expressed reduced levels of a group of genes which are preferentially expressed in the liver, including urea cycle enzyme genes (Biochim. Biophys. Acta 1138, 167–171, 1992). The expression of α-fetoprotein and aldolase A was elevated, indicating that the liver of jvs mice is undifferentiated or dedifferentiated (FEBS Lett. 311, 63–66, 1992). Studies of the hormone signal transduction pathway showed that serum cortisol and plasma glucagon levels of jvs mice were 2 and 3 times higher, respectively, than those of normal mice, and that the hormone binding activity of glucocorticoid receptor (GR) in the cytosol of jvs liver was 60% of normal mice, which reflected the amount of receptor protein in the cytosol. On the other hand, GR protein accumulated in the nuclear fraction in jvs mice. Exogenously administered dexamethasone induced carbomoyl phosphate synthetase (CPS) and tyrosine aminotransferase (TAT)_mRNAs in jvs mice, indicating that CPS and TAT genes in jvs mice are responsive to induction by glucocorticoid and cAMP. Analysis of transacting factors by gel retardation assay revealed that HNF-1, COUP-TF and SP-1 were detected at almost the same level in the hepatic nuclear fraction of jvs mice as in normal littermates, and C/EBP and CREB were a little higher in jvs mice, suggesting that these factors are probably not targets of jvs mutation causing abnormal gene expression in the liver. On the other hand, AP-1 binding activity was much higher in jvs mice from an early age, preceding the abnormal expression of urea cylce enzyme, and carnitine administration normalized AP-1 binding activity. We suggest that elevated AP-1 binding induced by carnitine deficiency is closely connected with the abnormal gene expression in the liver.

Effect of intravenous L-carnitine on carnitine homeostasis and fuel metabolism during exercise in humans

This study was undertaken to challenge the hypothesis that short-term administration of carnitine during exercise can modify skeletal muscle carnitine homeostasis and fuel metabolism in normal humans. With a randomized, blinded, crossover design, subjects received carnitine or placebo at the start of a bicycle ergometer exercise session. During the 2 hours after intravenous administration of 185 mumol/kg carnitine, carnitine kinetics could be described with a central compartment volume of distribution of 200 ml/kg, a total clearance from this compartment of 1.9 ml/min/kg, and a renal clearance of 1.3 ml/min/kg. Carnitine administration had no effect on muscle total carnitine content or the workload-dependent accumulation of acylcarnitines in skeletal muscle. Carnitine had no effect on the respiratory exchange ratio, muscle lactate accumulation, plasma lactate concentration, muscle glycogen utilization, or plasma beta-hydroxybutyrate concentration during exercise. Thus the skeletal muscle carnitine pool is segregated from dramatic changes in the plasma carnitine pool, and short-term administration of carnitine has no significant effect on fuel metabolism during exercise in humans.

Does Carnitine Administration Improve the Symptoms Attributed to Anticonvulsant Medications?: A Double-Blinded, Crossover Study

This study was designed to assess the reported improvement in "well-being" perceived by parents when children who are taking anticonvulsant medications are administered carnitine. Forty-seven children with seizures who were taking either valproic acid or carbamazepine were enrolled in a placebo-controlled, double-blinded, cross-over study of the effects of oral carnitine administration (100 mg/kilo) on their well-being as perceived by their parents. The well-being scores were assessed weekly by phone and in person at the start and end of each 4-week phase. The children's well-being scores improved weekly when either placebo or carnitine were administered. None of the analyses of improved well-being achieved statistical significance. We believe this study documents the necessity for controlled trials when assessing the subjective, beneficial effects of medications. Carnitine is expensive, costing approximately $.30/kilogram of body weight per day ($6 per day for a 20 kilo child). It would not appear warranted to administer carnitine prophylactically to children on anticonvulsant medications for alleviating common, nonspecific symptoms. Because there are no reliable clinical or laboratory tests of symptomatic carnitine deficiency caused by anticonvulsant administration, how to identify children in need of carnitine, and when to administer carnitine therapeutically to children receiving valproate or other anticonvulsants is unclear.

EFFECT OF PIVAMPICILLIN TREATMENT ON METABOLIC FGFI CONSUMPTION

During pivampicillin (PIVA) administrtion pivalate is liberated from the drug which can form an ester with Coenzyme-A and subsequently with carnitine. Primary pivaloylcarnitine loss causes carnitine deficiency and hypoletonemia. No data have been available on the effects of PIVA on the overall metabolism of humans. In 8 children the based RO increased from 0.8 + 0.01 to 0.97+0.01 (p<0.05) on the 3rd day of PIVA (6 × 500 mg) administration measured by indirect calorimetry. Marked decrease was found in the daily utilization of. (1.2 + 0.17 vs 0.31+0.17 g/kg). While the consumption of carbohydrates increased (4.00+0.50 vs 6.20+0.51). No change was found in utilization of nitrogen compound and the total energy utilized was not affected by the treatment. All of the above parameters showed normalization 3 days after the introduction of supplemental carnitine (3×1g) to the PIVA treatment. The data show, that the PIVA treatment causes profound changes in metabolie fuel consumption, the inhibited fat oxidation was replaced by increased utilization of carbohydrates. Administration of carnitine can reverse these changes by aiding the elimination of pivalate.

The Presence of L-Carnitine in Ocular Tissues of the Rabbit

Carnitine plays an important role in the metabolism of fatty acids. Its presence is considerable in tissues that use fatty acids as an important source of energy, such as the heart and skeletal muscle. Free carnitine and acid soluble acylcarnitines are present in various tissues of the rabbit eye. The lowest concentration of carnitine was observed in the vitreous humor and the highest in the lens. The ratio, acid soluble acylcarnitine/free carnitine, was lower in the cornea, aqueous humor, vitreous humor and lens, than in iris, ciliary body and choroid-retina. The topical administration of carnitine increased both free carnitine and acetylcarnitine in cornea, and only free carnitine in aqueous humor and choroid retina. Only after intravenous administration, did the levels of free and acyl-carnitine increase in the iris and ciliary body. Neither of the two carnitine species was changed in vitreous humor. The determination of the activity of carnitine acetyltransferase in the eye showed that in the ciliary body the values of activity were three times higher than those in the iris and choroid-retina. The elevated ratio of acid soluble acylcarnitines with respect to free carnitine in iris, ciliary body, choroid-retina as well as the higher activity of carnitine acetyltransferase in the ciliary body, suggest that carnitine plays an important role in those tissues of the eye where cells of a muscular nature are present and may represent, after esterification, an important energy reserve.