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Abstracts

LE Magazine October 2005
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Effect of propionyl-L-carnitine on exercise performance in peripheral arterial disease.

BACKGROUND: Supplemen tation with propionyl-L-car nitine (PLC) may be of use in improving the exercise capacity of people with peripheral arterial disease. METHODS: After a 2-wk exercise familiarization phase, seven subjects displaying intermittent claudication were studied over a 12-wk period consisting of three 4-wk phases, baseline (B), supplementation (S), and placebo (P). PLC was supplemented at 2 g x d(-1), and subjects were blinded to the order of supplementation. Unilateral calf strength and endurance were assessed weekly. Walking performance was assessed at the end of each phase using an incremental protocol, during which respiratory gases were collected. RESULTS: Although there was not a significant increase in maximal walking time (approximately 14%) in the whole group, walking time improved to a greater extent than the individual baseline coefficient of variation in four of the seven subjects. The changes in walking performance were correlated with changes in the respiratory exchange ratio both at steady state (r = 0.59) and maximal exercise (r = 0.79). Muscle strength increased significantly from 695 +/- 198 N to 812 +/- 249 N by the end of S. Changes in calf strength from B to S were modestly related to changes in walking performance (r = 0.56). No improvements in calf endurance were detected throughout the study. CONCLUSIONS: These preliminary data suggest that, in addition to walking performance, muscle strength can be increased in PAD patients after 4 wk of supplementation with propionyl-L-carnitine.

Med Sci Sports Exerc. 2001 Sep;33(9):1415-22

Carnitine and peripheral arterial disease.

Patients with peripheral arterial disease (PAD) who become symptomatic with claudication (approximately one-third of the population) have a marked impairment in exercise performance and overall functional capacity. Patients with claudication have a peak oxygen consumption measured during graded treadmill exercise testing that is 50% of that in age-matched normal subjects, and also report great difficulty in walking relatively short distances, even at a slow walking speed. The reduced walking capacity is associated with impairment in activities of daily living and quality of life. Thus, claudication is highly limiting to the physical functioning of daily activities. Improving mobility and improving the reduced quality of life are therefore major goals of treatment. Patients with PAD develop metabolic abnormalities in the skeletal muscles of the lower extremity. These abnormalities include impairment in ischemic muscle mitochondrial electron transport chain activity and accumulation of intermediates of oxidative metabolism (acylcarnitines). Patients with the greatest accumulation of muscle acylcarnitines have the most impaired exercise performance. Thus, claudication is not simply the result of reduced blood flow, and alterations in skeletal muscle metabolism are part of the pathophysiology of the disease. L-carnitine and propionyl-L-carnitine may improve the metabolism and exercise performance of ischemic muscles. L-carnitine in a dose of 2 grams twice daily improved treadmill performance, but propionyl-L-carnitine (an acyl form of carnitine) was more effective than L-carnitine in improving treadmill walking distance. In two multicenter trials of a total of 730 patients, initial and maximal treadmill walking distance improved more with propionyl-L-carnitine than placebo. The drug also improved quality of life and had minimal side effects as compared with placebo. Propionyl-L-carnitine has not been approved for use in the United States .

Ann N Y Acad Sci. 2004 Nov;1033:92-8

Exploratory open label, randomized study of acetyl- and propionylcarnitine in chronic fatigue syndrome.

OBJECTIVES: We compared the effects of acetylcarnitine, propionylcarnitine and both compounds on the symptoms of chronic fatigue syndrome (CFS). METHODS: In an open, randomized fashion we compared 2 g/d acetyl-L-carnitine, 2 g/d propionyl-L-carnitine, and its combination in 3 groups of 30 CFS patients during 24 weeks. Effects were rated by clinical global impression of change. Secondary endpoints were the Multidimensional Fatigue Inventory, McGill Pain Questionnaire, and the Stroop attention concentration test. Scores were assessed 8 weeks before treatment; at randomization; after 8, 16, and 24 weeks of treatment; and 2 weeks later. RESULTS: Clinical global impression of change after treatment showed considerable improvement in 59% of the patients in the acetylcarnitine group and 63% in the propionylcarnitine group, but less in the acetylcar nitine plus propionylcarnitine group (37%). Acetylcarnitine significantly improved mental fatigue (p =.015) and propionylcarnitine improved general fatigue (p =.004). Attention concentration improved in all groups, whereas pain complaints did not decrease in any group. Two weeks after treatment, worsening of fatigue was experienced by 52%, 50%, and 37% in the acetylcarnitine, propionylcarnitine, and combined group, respectively. In the acetylcarnitine group, but not in the other groups, the changes in plasma carnitine levels correlated with clinical improvement. CONCLUSIONS: Acetylcarnitine and propionylcarnitine showed beneficial effect on fatigue and attention concentration. Less improvement was found by the combined treatment. Acetylcarnitine had main effect on mental fatigue and propionylcarnitine on general fatigue.

Psychosom Med. 2004 Mar-Apr;66(2):276-82

Carnitine versus androgen administration in the treatment of sexual dysfunction, depressed mood, and fatigue associated with male aging.

OBJECTIVES: To To compare testosterone undecanoate versus propionyl-L-carnitine plus acetyl-L-carnitine and placebo in the treatment of male aging symptoms. METHODS: A total of 120 patients were randomized into three groups. The mean patient age was 66 years (range 60 to 74). Group 1 was given testosterone undecanoate 160 mg/day, the second group was given propionyl-L-carnitine 2 g/day plus acetyl-L-carnitine 2 g/day. The third group was given a placebo (starch). Drugs and placebo were given for 6 months. The assessed variables were total prostate-specific antigen, prostate volume, peak systolic velocity, end-diastolic velocity, resistive index of cavernosal penile arteries, nocturnal penile tumescence, total and free testosterone, prolactin, luteinizing hormone, International Index of Erectile Function score, Depression Melancholia Scale score, fatigue scale score, and incidence of side effects. The assessment was performed at intervals before, during, and after therapy. RESULTS: Testosterone and carnitines significantly improved the peak systolic velocity, end-diastolic velocity, resistive index, nocturnal penile tumescence, International Index of Erectile Function score, Depression Melancholia Scale score, and fatigue scale score. Carnitines proved significantly more active than testosterone in improving nocturnal penile tumescence and International Index of Erectile Function score. Testosterone significantly increased the prostate volume and free and total testosterone levels and significantly lowered serum luteinizing hormone; carnitines did not. No drug significantly modified prostate-specific antigen or prolactin. Carnitines and testosterone proved effective for as long as they were administered, with suspension provoking a reversal to baseline values. Only the group 1 prostate volume proved significantly greater than baseline 6 months after testosterone suspension. Placebo administration proved ineffective. Negligible side effects emerged. CONCLUSIONS: Testosterone and, especially, carnitines proved to be active drugs for the therapy of symptoms associated with male aging.

Urology. 2004 Apr;63(4):641-6

Diabetes mellitus and subjects’ ageing: a study on the ATP content and ATP-related enzyme activities in human erythrocytes.

Na+/K(+)- and Ca(2+)-ATPase are the major ATP-dependent membrane-bound enzymes that regulate the cation transmembrane gradient which is altered both in red blood cell (RBC) senescence and in RBCs of diabetic patients. In an attempt to clarify the possible connection between diabetes mellitus and ageing, we investigated the relationship between RBC ATP content, Na+/K(+)-ATPase, Ca(2+)-ATPase activities and ageing in healthy, insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) subjects. A significant correlation was found (r = -0.82; P < 0.001) between RBC ATP content and subject’s age only in the control group. A significant reduction in Na+/K(+)-ATPase activity was observed in the older group (C2) of control subjects, in comparison with the younger (C1) one. In both IDDM and NIDDM subjects, the enzymatic activity was significantly decreased when compared with health subjects of similar age (P < 0.001). A significant negative correlation was found between age and enzymatic activity in healthy subjects (r = -0.60; P < 0.001). No difference was observed in the RBC membrane Ca(2+)-ATPase activity between younger (C1) and older (C2) healthy subjects. Ca(2+)-ATPase activity was significantly increased both in IDDM patients compared with C1 (P < 0.001) and in NIDDM patients compared with C2 (P < 0.001). The present data indicate that ageing causes a reduction in the erythrocyte ATP content in both healthy and diabetic subjects. In diabetic patients Na+/K(+)-ATPase activity decreases independently of age.

Eur J Clin Invest. 1997 Apr;27(4):327-32

Cardiovascular and pulmonary response to oral administration of ATP in rabbits.

Extracellular purines such as ATP and adenosine participate in the regulation of cardiovascular and respiratory functions through specific P1 and P2 purine receptors. These properties have mainly been described after intravenous infusion. Experiments reported herein were designed to explore the possible effect of oral ATP administration (3 or 20 mg. kg(-1). day(-1)) on vascular, cardiac, and pulmonary functions in rabbits. Whereas a unique oral dose of ATP has no effect, chronic supplementation during 14 days reduces peripheral vascular resistance, pulmonary resistance, and respiratory frequency and increases arterial PO (2). No effect on central blood pressure and heart rate is observed, but an increase of the left ventricular work index is noticed subsequent to the diminution of vascular resistance. Rather similar cardiovascular modifications are observed in rabbits given 20 mg. kg(-1). day(-1) adenosine for 14 days but without variation of respiratory parameters. These original effects of repeated oral treatment with ATP may result from an adaptive metabolic response to nucleoside supplementation that might affect the turnover of extracellular purines leading to P1- and/or P2-receptor activation.

J Appl Physiol. 2000 Jun;88(6):1962-8

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