Ribose Supplementation Research Articles

Oral ribose supplementation in dystroglycanopathy: A single case study.

Three forms of muscular dystrophy-dystroglycanopathies are linked to the ribitol pathway. These include mutations in the isoprenoid synthase domain-containing protein (ISPD), fukutin-related protein (FKRP), and fukutin (FKTN) genes. The aforementioned enzymes are required for generation of the ribitol phosphate linkage in the O-glycan of alpha-dystroglycan. Mild cases of dystroglycanopathy present with slowly progressive muscle weakness, while in severe cases the eyes and brain are also involved. Previous research showed that ribose increased the intracellular concentrations of cytidine diphosphate-ribitol (CDP-ribitol) and had a therapeutic effect. Here, we report the safety and effects of oral ribose supplementation during 6 months in a patient with limb girdle muscular dystrophy type 2I (LGMD2I) due to a homozygous FKRP mutation. Ribose was well tolerated in doses of 9 g or 18 g/day. Supplementation with 18 g of ribose resulted in a decrease of creatine kinase levels of 70%. Moreover, metabolomics showed a significant increase in CDP-ribitol levels with 18 g of ribose supplementation (p < 0.001). Although objective improvement in clinical and patient-reported outcome measures was not observed, the patient reported subjective improvement of muscle strength, fatigue, and pain. This case study indicates that ribose supplementation in patients with dystroglycanopathy is safe and highlights the importance for future studies regarding its potential effects.

Effect of low-dose acute ribose supplementation prior to and during repeated sprint exercise on anaerobic performance and blood lactate level

Objective: This study aimed to investigate the possible positive effects of acute low-dose ribose supplementation prior to and during repeated sprint interval exercise on anaerobic performance, blood lactate (BLa) levels, and perceived exertion. Materials and Methods: In a double-blind, randomized and crossover design, a total of 20 healthy males (mean [standard deviation]: age= 20.8 [0.8] yr, body weight= 79.9 [11.3] kg) ingested either a ribose supplementation or placebo prior to and during a Wingate test involving 4×30-s all-out cycling against a load representing 7.5% of participant’s body mass, with a 4-min of recovery at low-intensity between each sprint. The supplementation consisted of 2.5 g of ribose or placebo ingested 4 min before the Wingate tests and immediately after the 1st, 2nd, and 3rd sprint, for a total of 10 g. Results: Ribose supplementation significantly increased the peak power output (mean difference (Δ)=75.0 W; p=0.016; effect size (d)=0.59), and the mean power output of the second sprint (Δ=39.5 W; p=0.03; d=0.52), with no notable change in other sprint performances. Rating of perceived exertion significantly increased after the tests (p&lt;0.001; partial eta squared (ηp2)=0.83), with no difference among the conditions (p&gt;0.05). There was a slight but significant decrease in resting BLa before the Wingate test with ribose supplementation (Δ=0.05 mmol/L; p=0.047; d=0.48). The Wingate tests significantly increased BLa across time for both groups (p&lt;0.001), yet levels of BLa prior to, during, and following the Wingate tests were similar among groups (p&gt;0.05). Conclusion: These results show that acute ribose supplementation does not remarkably impact anaerobic performance during repeated sprint exercise.

Ribitol alters multiple metabolic pathways of central carbon metabolism with enhanced glycolysis: A metabolomics and transcriptomics profiling of breast cancer.

Breast cancer is heterogenous in development and cell population with prognoses being highly dependent on numerous factors from driving mutations, biomarker expression and variation in extracellular environment, all affecting response to therapies. Recently, much attention has been given to the role of metabolic alteration in cancers, expanding from the Warburg effect to highlight unique patterns in different cancer cell populations for improving diagnostic and therapeutic approaches. We recently reported on modulation of mannosylation of α-dystroglycan with the metabolite ribitol in breast cancer lines. Here we investigate the effects of pentose sugars ribitol, ribose, and xylitol media supplementation in breast cancer cells by metabolomics and differential gene expression profiling. This combined approach revealed distinctive patterns of alterations in metabolic pathways by ribitol, contrasted with the closely related pentose ribose and pentitol xylitol. Significantly, ribitol supplementation enhances utilization of glucose by glycolysis, whereas ribose improves oxidative phosphorylation and fatty acid synthesis. Ribitol supplementation also increased levels of reduced glutathione (associated with a decrease in oxidative phosphorylation, gluconeogenesis), where ribose supplementation elevated levels of oxidized glutathione (GSSG) indicating an increase in oxidative stress. Treatment with ribitol also enhanced nucleotide biosynthesis. The apparent TCA cycle dysregulation, with distinctive pattern in response to the individual pentitol and pentose, such as ribitol increasing succinate and fumarate while decreasing citrate, demonstrate the adaptive capability of cancer cells to nutritional environment. This metabolic reprogramming presents new avenues for developing targeted therapies to cancers with metabolites, especially in combination with other drug treatments.

Effects of C5 organic carbon and light on growth and cell activity of Haematococcus pluvialis under mixotrophic conditions

Mixotrophic culture can be an effective way for increasing algae growth rate and productivity. In this study, the utilization of C5 organic carbon by Haematococcus pluvialis was investigated under mixotrophic conditions with different light intensities. H. pluvialis was found to have the capacity to assimilate ribose as a carbon source. Ribose supplementation increased biomass content and cell activity, which prolonged the green growing stage through increasing cell division. Higher cell activity levels also reduced the possibility of contamination. Forty one percent of supplemented ribose was assimilated after 7days under mixotrophic cultivation. In addition, cultures supplemented with ribose had an improved motile cell ratio (31%) over cultures supplemented with sodium acetate, 7%. Light intensities affected ribose assimilation and cell activity. The highest ribose assimilation level (46%) was obtained at high light intensity. However, the maximum ratio of motile cell (37%) and the highest total cell number (1.15×106/mL) occurred at low light intensity. The results provided information about the synergistic effects of light and types of C5 carbon on biomass growth for H. pluvialis under mixotrophic culture. The possibility of using ribose as a carbon source offers a new strategy for biomass improvement and contamination control under mixotrophic conditions.

D-Ribose Supplementation in the Equine: Lack of Effect on Glycated Plasma Proteins Suggesting Safety in Humans

Background: d-Ribose is a popular dietary supplement for humans and the equine because of its crucial role in cellular bioenergetics. However, as a reducing sugar, it has been suggested that ingestion of d-ribose might promote the formation of glycated proteins in vivo with potential adverse consequences.Objective: The aim of this study was to examine if d-Ribose would promote the formation of glycated proteins in vivo following exercise in training thoroughbred racehorses.Methods: Two groups of horses received the supplement (30 and 50 g d-Ribose daily) for 17 weeks, during which period the horses were subjected to low-intensity exercises followed by high-intensity exercises. Blood samples were analyzed for glycated plasma proteins at baseline and following the 2 exercise regimens.Results: This study shows that long-term ingestion of d-Ribose at 30-50 g a day does not promote the formation of glycated plasma proteins in thoroughbred racehorses. Ribose supplementation also protected the horses from cramping while enhancing muscle recovery at the same time. No adverse effects were reported.Conclusion: Ribose supplementation is safe and does not cause glycation in vivo. This investigation also establishes safety of d-Ribose in thoroughbred racehorses, suggesting similar implications in humans as well.

Ribose Supplementation Alone or with Elevated Creatine Does Not Preserve High Energy Nucleotides or Cardiac Function in the Failing Mouse Heart

BackgroundReduced levels of creatine and total adenine nucleotides (sum of ATP, ADP and AMP) are hallmarks of chronic heart failure and restoring these pools is predicted to be beneficial by maintaining the diseased heart in a more favourable energy state. Ribose supplementation is thought to support both salvage and re-synthesis of adenine nucleotides by bypassing the rate-limiting step. We therefore tested whether ribose would be beneficial in chronic heart failure in control mice and in mice with elevated myocardial creatine due to overexpression of the creatine transporter (CrT-OE).Methods and ResultsFour groups were studied: sham; myocardial infarction (MI); MI+ribose; MI+CrT-OE+ribose. In a pilot study, ribose given in drinking water was bioavailable, resulting in a two-fold increase in myocardial ribose-5-phosphate levels. However, 8 weeks post-surgery, total adenine nucleotide (TAN) pool was decreased to a similar amount (8–14%) in all infarcted groups irrespective of the treatment received. All infarcted groups also presented with a similar and substantial degree of left ventricular (LV) dysfunction (3-fold reduction in ejection fraction) and LV hypertrophy (32–47% increased mass). Ejection fraction closely correlated with infarct size independently of treatment (r2 = 0.63, p<0.0001), but did not correlate with myocardial creatine or TAN levels.ConclusionElevating myocardial ribose and creatine levels failed to maintain TAN pool or improve post-infarction LV remodeling and function. This suggests that ribose is not rate-limiting for purine nucleotide biosynthesis in the chronically failing mouse heart and that alternative strategies to preserve TAN pool should be investigated.

Effects of ribose supplementation on anaerobic performance, plasma pH, lactate, ammonia and inorganic phosphate levels

The purpose of this study was to estimate the effects of ribose supplementation on interval anaerobic performance and fatiguing substance concentrations. The study cohort consisted of physically active, young male volunteers (n = 15). With a double-blind cross over study design, each participant completed two all-out anaerobic exercise sessions, one week apart, one by supplementing maltodextrine and the other by supplementing ribose (150 mg/kg in each test). Two repetitions of 30-s maximal performance with a 4-min interval were completed. Blood samples were taken at rest and five minutes after the second sprint repetition. Neither the biochemical parameters: pH (−0.32± 0.09 vs.−0.26± 0.11), lactate (La) (13.8± 1.9 vs. 13.3± 2.7 mM, ammonia (423 ± 190 vs. 404 ± 166 μmol/L), inorganic phosphate (Pi) (0.68 ± 0.53 vs. 0.72 ± 0.63 mM) nor the anaerobic output (746.2 ± 82.5 vs. 760.2 ± 86.8 watts) were affected by placebo and ribose supplementations significantly (p > 0.05). In conclusion, based on this protocol, anaerobic performance and/or biochemical status are not affected by ribose supplementation.

The Role of Ribose on Oxidative Stress During Hypoxic Exercise: A Pilot Study

Oxygen free radicals are produced during stress, are unstable, and potentially interact with other cellular components or molecules. This reactivity can influence cellular function, including a prolongation in tissue recovery following exercise. We tested the effect of ribose (d-ribose), a pentose carbohydrate, in a double-blinded, crossover study on markers of free radical production during hypoxic exercise. Seven healthy volunteers cycled at their lactate threshold for 25 minutes while inhaling 16% O(2) with a subsequent 60-minute resting period at room air. Subjects ingested either placebo or 7 g of ribose in 250 mL of water before and after the exercise session. Urinary malondialdehyde (MDA) and plasma reduced glutathione levels increased significantly during placebo ingestion (0.2 +/- 0.03 nM/mg and 0.26 +/- 0.29 microM, respectively) but were lower with ribose supplementation (0.04 +/- 0.03 nM/mg and 0.38 +/- 0.29 microM, respectively; P < .05). Uric acid levels were similar between groups (ribose vs. placebo, 4.55 +/- 0.06 mg/dL vs. 4.67 +/- 0.06 mg/dL). Ribose demonstrated a beneficial trend in lower MDA and reduced glutathione levels during hypoxic stress.

Ribose enhances retinoic acid–induced differentiation of HL-60 cells

Ribose, a critical building block for nucleotides, plays an important role in energy metabolism, transcription, translation, and second messenger systems. This 5-carbon sugar, synthesized from glucose via the pentose phosphate pathway, has a rate-limiting step at glucose-6-phosphate dehydrogenase. Therefore, we hypothesized that when cells are required to proliferate or differentiate, as in an immune response, the requirement for D-ribose may be greater than what could be supplied by the synthetic pathway. We hypothesized that providing an exogenous source of D-ribose during cell differentiation will enhance the process of differentiation. We used a retinoic acid-induced HL-60 cell differentiation culture as a model of neutrophil maturation. The addition of 10 to 25 mmol/L D-ribose was shown to reduce cell proliferation and move the cell population toward apoptosis in a dose-dependent manner. The expression of a cell surface marker representing maturity (CD11b) significantly increased and a cell surface marker indicative of immaturity (CD117) significantly decreased. Functionally, the cells had a greater oxidative burst function dependent on time and dose. The mechanism by which ribose enhances HL-60 cell differentiation is not known; however, as adenosine triphosphate levels did not change, adenosine triphosphate is not thought to be involved. We conclude that in this cell culture model, ribose supplementation enhanced cellular differentiation and function. Thus, ribose might be conditionally essential during time of higher need as in an immune response.

Ribose: More than a simple sugar?

This article reviews the current literature regarding the use of ribose as an ergogenic aid. Ribose manufacturers claim that it provides ergogenic benefit, but this has not been substantiated through scientific investigations. Data have shown promise that ribose supplementation leads to enhanced restoration of ATP levels following exercise, but this has seldom translated into increased athletic performance. However, as with many ergogenic aids, additional research is needed to clarify its value as a supplement.

Ribose Versus Dextrose Supplementation, Association With Rowing Performance

It has been hypothesized that ribose supplementation rapidly replenishes adenosine triphosphate stores and thereby improves exercise performance. We compared the effects of ribose versus dextrose on rowing performance. Double-blind randomized trial. Rowing team training area of large midwestern university. Thirty-one women collegiate rowers. We studied the effects of ribose versus dextrose supplementation (10 g each in 8 oz water) for 8 weeks before and after practice and 2000-m time trials. OUTCOME MEASUREMENTS AND RESULTS: In the time trials, the dextrose group showed significantly more improvement at 8 weeks than the ribose group (median, 15.2 vs. 5.2 s; P = 0.031). We doubt ribose impaired, and hypothesize dextrose enhanced, rowing performance. Further research is needed to define what role, if any, dextrose and ribose play as athletic supplements.

Effects of Ribose Supplementation Prior to and during Intense Exercise on Anaerobic Capacity and Metabolic Markers

This study examined whether ribose supplementation before and during intense anaerobic exercise impacts anaerobic capacity and metabolic markers. Twelve moderately trained male cyclists (22.3 +/- 2.2 y; 181 +/- 6 cm, 74.8 +/- 9 kg) participated in the study. Subjects were familiarized and fasted for 8 h after standardizing nutritional intake. In a double blind and crossover manner subjects ingested either a 150 mL placebo or ribose (3 g ribose + 150 microg folate). Subjects rested for 25 min and completed 5 x 30 s anaerobic capacity tests with 3 min passive rest. Six capillary blood samples were taken prior to and after sprints for adenine nucleotide breakdown determination. The experiment was repeated 1 wk later with alternative drink. Data were analyzed by repeated measures ANOVA. No significant interactions were observed for any performance or blood variables. D-ribose supplementation has no impact on anaerobic exercise capacity and metabolic markers after high-intensity cycling exercise.

Benefit of Ribose in a Patient with Fibromyalgia

Ribose was added to the existing treatment regimen of a woman with fibromyalgia, resulting in a decrease in symptoms. It has been postulated that patients with fibromyalgia may have an alteration in muscle adenine nucleotide metabolism, leading to depleted energy reserves and an imbalance in cellular adenosine 5'-triphosphate:adenosine 5'-diphosphate:adenosine 5'-monophosphate (ATP:ADP:AMP) ratios with an abnormal energy charge. As a key component in adenine nucleotide synthesis, ribose supplementation may be useful in such patients.

Effects of ribose supplementation on selected metabolic measurements and performance in maximally exercising Thoroughbreds1

The objective of this study was to investigate the effects of ribose supplementation on blood ammonia-N, plasma lactic acid, plasma glucose, volume of oxygen consumption (VO2), heart rate, and performance in Thoroughbred geldings performing a maximal treadmill standardized exercise test (SET). The hypothesis tested was that ribose supplementation would decrease ammonia-N and lactic acid accumulation during exercise, and improve performance. Eight Thoroughbred geldings were assigned randomly to one of two groups: glucose or ribose. The glucose group received 0.15 g glucose/kg of BW, and the ribose group received 0.15 g of ribose/kg BW top-dressed on the feed twice daily. After 2 wk of glucose or ribose supplementation, a SET was performed. Blood was analyzed for blood ammonia-N, plasma lactic acid, and plasma glucose before exercise (0 min), every minute during SET, and at 15 and 30 min after exercise. Heart rate and VO2 were recorded for the duration of SET. After a 10-d washout period, geldings switched groups. Following another 2 wk of supplementation, a second SET was performed, and same data recorded. Blood ammonia-N and plasma lactic acid increased as duration of SET increased and reached a peak at 15 min after exercise. Peak plasma glucose was observed at 15 min after exercise, and peak heart rate and VO2 were recorded at highest speed during SET. Geldings supplemented with ribose had blood ammonia-N, plasma lactic acid, plasma glucose, VO2, heart rate, and performance similar to those of geldings supplemented with glucose. Results from this study show that supplementation with 0.15 g ribose/kg BW twice daily in the diet of conditioned Thoroughbred geldings for 2 wk does not influence blood ammonia-N, plasma lactic acid, plasma glucose, VO2, heart rate, or performance during SET or the first 30 min of recovery.

Effects of ribose supplementation on selected metabolic measurements and performance in maximally exercising Thoroughbreds.

The objective of this study was to investigate the effects of ribose supplementation on blood ammonia-N, plasma lactic acid, plasma glucose, volume of oxygen consumption (VO2), heart rate, and performance in Thoroughbred geldings performing a maximal treadmill standardized exercise test (SET). The hypothesis tested was that ribose supplementation would decrease ammonia-N and lactic acid accumulation during exercise, and improve performance. Eight Thoroughbred geldings were assigned randomly to one of two groups: glucose or ribose. The glucose group received 0.15 g glucose/kg of BW, and the ribose group received 0.15 g of ribose/kg BW top-dressed on the feed twice daily. After 2 wk of glucose or ribose supplementation, a SET was performed. Blood was analyzed for blood ammonia-N, plasma lactic acid, and plasma glucose before exercise (0 min), every minute during SET, and at 15 and 30 min after exercise. Heart rate and VO2 were recorded for the duration of SET. After a 10-d washout period, geldings switched groups. Following another 2 wk of supplementation, a second SET was performed, and same data recorded. Blood ammonia-N and plasma lactic acid increased as duration of SET increased and reached a peak at 15 min after exercise. Peak plasma glucose was observed at 15 min after exercise, and peak heart rate and VO2 were recorded at highest speed during SET. Geldings supplemented with ribose had blood ammonia-N, plasma lactic acid, plasma glucose, VO2, heart rate, and performance similar to those of geldings supplemented with glucose. Results from this study show that supplementation with 0.15 g ribose/kg BW twice daily in the diet of conditioned Thoroughbred geldings for 2 wk does not influence blood ammonia-N, plasma lactic acid, plasma glucose, VO2, heart rate, or performance during SET or the first 30 min of recovery.

Effect of ribose supplementation on resynthesis of adenine nucleotides after intense intermittent training in humans

The effect of oral ribose supplementation on the resynthesis of adenine nucleotides and performance after 1 wk of intense intermittent exercise was examined. Eight subjects performed a random double-blind crossover design. The subjects performed cycle training consisting of 15 x 10 s of all-out sprinting twice per day for 7 days. After training the subjects received either ribose (200 mg/kg body wt; Rib) or placebo (Pla) three times per day for 3 days. An exercise test was performed at 72 h after the last training session. Immediately after the last training session, muscle ATP was lowered (P < 0.05) by 25 +/- 2 and 22 +/- 3% in Pla and Rib, respectively. In both Pla and Rib, muscle ATP levels at 5 and 24 h after the exercise were still lower (P < 0.05) than pretraining. After 72 h, muscle ATP was similar (P > 0.05) to pretraining in Rib (24.6 +/- 0.6 vs. 26.2 +/- 0.2 mmol/kg dry wt) but still lower (P < 0.05) in Pla (21.1 +/- 0.5 vs. 26.0 +/- 0.2 mmol/kg dry wt) and higher (P < 0.05) in Rib than in Pla. Plasma hypoxanthine levels after the test performed at 72 h were higher (P < 0.05) in Rib compared with Pla. Mean and peak power outputs during the test performed at 72 h were similar (P > 0.05) in Pla and Rib. The results support the hypothesis that the availability of ribose in the muscle is a limiting factor for the rate of resynthesis of ATP. Furthermore, the reduction in muscle ATP observed after intense training does not appear to be limiting for high-intensity exercise performance.

Effects of Ribose Supplementation on Repeated Sprint Performance in Men

This study used a randomized, placebo-controlled, crossover design to evaluate the effects of oral ribose supplementation on short-term anaerobic performance. After familiarization, subjects performed 2 bouts of repeated cycle sprint exercise (six 10-second sprints with 60-second rest periods between sprints) in a single day. After the second exercise, bout subjects ingested 32 g of ribose or cellulose (4 X 8-g doses) during the next 36 hours. After supplementation, subjects returned to the laboratory to perform a single bout of cycle sprinting (as described above). After a 5-day washout period, subjects repeated the protocol, receiving the opposite supplement treatment. Ribose supplementation lead to statistically significant increases in mean power and peak power in sprint 2 (10.9 and 6.6%, respectively) and higher (although not significant) absolute values in sprints 1, 3, and 4. In conclusion, ribose supplementation did not show reproducible increases in performance across all 6 sprints. Therefore, within the framework of this investigation, it appears that ribose supplementation does not have a consistent or substantial effect on anaerobic cycle sprinting.

The effects of four weeks of ribose supplementation on body composition and exercise performance in healthy, young, male recreational bodybuilders: a double-blind, placebo-controlled trial

Background: Ribose is a pentose sugar that is present in ribonucleic acids, riboflavin, nucleotides, and adenosine triphosphate. Whether exogenous ribose administration affects skeletal muscle concentrations of total adenine nucleotides is unknown. Whether supplementation with ribose positively affects body composition or exercise performance in recreational bodybuilders also is unknown. Objective: The purpose of this double-blind, placebo-controlled trial was to determine the effects of 4 weeks of ribose supplementation on body composition and exercise performance in healthy, young, male recreational bodybuilders. Methods: Healthy, male recreational bodybuilders aged 18 to 35 years were recruited and randomized to a ribose-supplemented group (10 g/d in powder formulation) or a placebo group (dextrose). Each subject participated in a heavy-resistance training program designed to increase skeletal muscle mass. Body composition (ie, body weight, body fat, lean body mass, fat mass, and bone mineral content) was assessed using dual-energy x-ray absorptiometry analysis. Muscular strength (as measured by a 1-repetition maximum-strength [1-RM] bench press) and total work performed (as measured by total repetitions for 10 sets of bench presses before muscular failure; 1-minute resting interval between sets) to muscular failure at a submaximal load (100% of pretest body weight) were ascertained. In addition, 24-hour dietary recalls were obtained before and after the study. Results: Twenty men (mean age ± SE, 23.9 ± 1.4 years) were enrolled; 19 subjects completed 24-hour dietary recalls and exercise performance testing; 12 subjects completed the study (24-hour dietary recalls, exercise performance, and body composition). No baseline differences were found between the 2 groups for any of the measured parameters. The ribose-supplemented group experienced a significant pretreatment-to-posttreatment increase in the total work performed, whereas the placebo group did not change significantly (24.5 ± 7.6 to 29.3 ± 7.5 repetitions; 19.6% ribose [ P = 0.028] vs 34.1 ± 8.6 to 38.2 ± 8.0 repetitions, 12.0% placebo). In addition, the ribose-supplemented group experienced a significant increase in 1-RM bench press strength, whereas the placebo group did not change significantly (114.1 ± 13.6 to 117.7 ± 14.0 kg, 3.2% ribose [ P = 0.008] vs 129.6 ± 14.2 to 131.8 ± 14.5 kg, 1.7% placebo). No pretreatment-to-posttreatment within-group or between-group differences were found for any of the measures of body composition or the 24-hour dietary data. Conclusion: The results of this study indicate that supplementation with ribose 10 g/d for 4 weeks resulted in significant increases in muscular strength and total work performed in recreational bodybuilders in this study, although no significant changes in body composition or 24-hour dietary data were found.

Influence of ribose on adenine salvage after intense muscle contractions.

The influence of ribose supplementation on skeletal muscle adenine salvage rates during recovery from intense contractions and subsequent muscle performance was evaluated using an adult rat perfused hindquarter preparation. Three minutes of tetanic contractions (60 tetani/min) decreased ATP content in the calf muscles by approximately 50% and produced an equimolar increase in IMP. Effective recovery of muscle ATP 1 h after contractions was due to reamination of IMP via the purine nucleotide cycle and was complete in the red gastrocnemius but incomplete in the white gastrocnemius muscle section. Adenine salvage rates in recovering muscle averaged 45 +/- 4, 49 +/- 5, and 30 +/- 3 nmol. h(-1). g(-1) for plantaris, red gastrocnemius, and white gastrocnemius muscle, respectively, which were not different from values in corresponding nonstimulated muscle sections. Adenine salvage rates increased five- to sevenfold by perfusion with approximately 4 mM ribose (212 +/- 17, 192 +/- 9, and 215 +/- 14 nmol. h(-1). g(-1) in resting muscle sections, respectively). These high rates were sustained in recovering muscle, except for a small (approximately 20%) but significant (P < 0.001) decrease in the white gastrocnemius muscle. Ribose supplementation did not affect subsequent muscle force production after 60 min of recovery. These data indicate that adenine salvage rates were essentially unaltered during recovery from intense contractions.

Purine salvage to adenine nucleotides in different skeletal muscle fiber types.

Rates of purine salvage of adenine and hypoxanthine into the adenine nucleotide (AdN) pool of the different skeletal muscle phenotype sections of the rat were measured using an isolated perfused hindlimb preparation. Tissue adenine and hypoxanthine concentrations and specific activities were controlled over a broad range of purine concentrations, ranging from 3 to 100 times normal, by employing an isolated rat hindlimb preparation perfused at a high flow rate. Incorporation of [(3)H]adenine or [(3)H]hypoxanthine into the AdN pool was not meaningfully influenced by tissue purine concentration over the range evaluated (approximately 0.10-1.6 micromol/g). Purine salvage rates were greater (P < 0.05) for adenine than for hypoxanthine (35-55 and 20-30 nmol x h(-1) x g(-1), respectively) and moderately different (P < 0.05) among fiber types. The low-oxidative fast-twitch white muscle section exhibited relatively low rates of purine salvage that were approximately 65% of rates in the high-oxidative fast-twitch red section of the gastrocnemius. The soleus muscle, characterized by slow-twitch red fibers, exhibited a high rate of adenine salvage but a low rate of hypoxanthine salvage. Addition of ribose to the perfusion medium increased salvage of adenine (up to 3- to 6-fold, P < 0.001) and hypoxanthine (up to 6- to 8-fold, P < 0.001), depending on fiber type, over a range of concentrations up to 10 mM. This is consistent with tissue 5-phosphoribosyl-1-pyrophosphate being rate limiting for purine salvage. Purine salvage is favored over de novo synthesis, inasmuch as delivery of adenine to the muscle decreased (P < 0.005) de novo synthesis of AdN. Providing ribose did not alter this preference of purine salvage pathway over de novo synthesis of AdN. In the absence of ribose supplementation, purine salvage rates are relatively low, especially compared with the AdN pool size in skeletal muscle.