Effect of Insulin on the Uptake of Creatine-1-14C by Skeletal Muscle in Normal and X-Irradiated Rats

Koszalka, Thomas R.; Andrew, Carole L.

doi:10.3181/00379727-139-36344

Cited by 36 publications

(20 citation statements)

References 6 publications

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“…Ku and Passow (1980) reported that the saturable component of Cr transport is dependent upon cell age and is higher in young cells. The uptake and rate of transport of Cr by the muscle is mediated by insulin action (Haugland and Chang 1975;Koszalka and Andrew 1972) and is enhanced in the presence of carbohydrate (Green et al 1996). Aging is associated with glucose intolerance, and there is a decline in insulinstimulated glucose transport with age (Dolan et al 1995) that does not appear to be due to a decline in Glut-4 transporters alone (Youngren and Barnard 1995).…”

Section: Discussionmentioning

confidence: 97%

Effects of 30 days of creatine ingestion in older men

1999

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In this investigation we evaluated the effects of oral creatine (Cr) supplementation on body composition, strength of the elbow flexors, and fatigue of the knee extensors in 20 males aged 60-82 years who were randomly administered Cr or placebo (P) in a double-blind fashion. Subjects ingested either 20 g of Cr or P for 10 days, followed by either 4 g of Cr or P, respectively, for 20 days. Tests were conducted pre-supplementation and following 10 and 30 days of supplementation. Leg fatigue was determined using an isokinetic dynamometer; subjects performed 5 sets of 30 maximal voluntary contractions at 180 degrees x s(-1), with 1 min of recovery between sets. The strength of the elbow flexors was assessed using a modified preacher bench attached to a strain gauge. There was a significant interaction (P < 0.05; group x time) in leg fatigue following supplementation. However, this interaction appears to have resulted from a combination of the improved fatigue score by the Cr-supplemented group and the decreased fatigue score by the P-supplemented group, because when the simple main effects were analyzed for the groups individually, there was no significant difference over time for either of the groups. There were no significant differences in body mass, body density, or fat-free mass as assessed by hydrostatic weighing, or strength between the Cr-supplemented or P-supplemented groups. These data suggest that 30 days of Cr-supplementation may have a beneficial effect on reducing muscle fatigue in men over the age of 60 years, but it does not affect body composition or strength.

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Section: Discussionmentioning

confidence: 97%

Effects of 30 days of creatine ingestion in older men

1999

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“…When intraperitoneally injected, it leads to hypoglycemia (9) and its supplementation in the diet has shown improvement when there is alteration in the glucose tolerance (10) . Since the 70's, studies with animal models as well as 'in vitro' have demonstrated that insulin increases the blood creatine transportation to the skeletal muscle of rats (11)(12) . It has also been demonstrated that creatine increases the muscular storages of glycogen (13) .…”

Section: Introductionmentioning

confidence: 99%

Resistência à insulina com a suplementação de creatina em animais de experimentação

Costallat¹,

Miglioli²,

Silva³

et al. 2007

Rev Bras Med Esporte

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Introduction and objective:Creatine supplementation has been used in order to improve muscular performance. This substance affects glucose metabolism and stimulates the in vitro as well as the in vivo insulin secretion. Nevertheless, long-term insulin hypersecretion may also induce insulin resistance. The present work analyzed the effects of creatine oral supplementation in order to evaluate the possibility of occurrence of resistance to in vivo insulin. Methods: Forty-eight Wistar rats (24 female/ 24 male) were divided in two groups of 24 (control and study) and subdivided in six groups of eight. They were fed with standard food during four weeks, having water ad libitum. Moreover, the study group received dietetic supplement of creatine (0.4 g creatine for 30 ml of water per rat / day). In the 7 th , 14 th , 21 st and 28 th day of the experiment, 12 rats were anesthetized (sodium thiopental 0.15 mL/ 100 g) after six hour-fasting, being submitted to intravenous insulin tolerance test (0.5 mL of 30% regular human insulin and 70% saline solution). The blood samples were collected from the tail veins of the rats, in the basal, three, six, nine, 12 and 15 minutes after insulin administration times. The glucose measurement was performed through the glucose oxidase method. The study was previously approved by the Research Ethics Committee of CCMB-PUC-SP. Results: The mean of the glucose decrease constant (K ITT ) was calculated through the formula 0.693/ T 1/2 . The study group, when compared with the control group, presented insulin resistance at day 21 (p < 0.0004) and day 28 (p < 0.0001). Conclusion: This study shows that extended creatine supplementation may lead to insulin resistance. Besides that, it should be carefully used in individuals with glucose metabolism disturbances.

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“…It was hypothesized that insulin, released as a consequence of carbohydrate ingestion, was responsible for enhancement of muscle creatine transport. This was supported by findings from animal studies showing that insulin could increase whole body creatine retention in vivo [100] and could stimulate cellular creatine uptake in vitro [101]. It has been proposed that insulin facilitates Na-dependent creatine transport by increasing muscle Na + /K + ATPase activity [90,102] and therefore by increasing the electrochemical gradient used to drive creatine across the membranes.…”

Section: Insulinmentioning

confidence: 90%

“…Cyclosporine A inhibition [82] Growth hormone stimulation [98] Guanidino compounds inhibition [14,37,59,60,64,72] Hypertonic environment stimulation [106] Insulin stimulation [71,90,[99][100][101][102][103] Modifications of the amino acid sequence inhibition [85][86][87] Modifications of the ionic environment inhibition [13][14][15]60] Protein kinases stimulation or inhibition* [93,94,97] *Available evidence shows that protein kinases favor expression and function of the transporter; by contrast, it may be hypothesized that blocking protein kinases activity may inhibit creatine transporter.…”

Section: Tools For Inhibition and Stimulation Of Crt Effect Referencesmentioning

confidence: 99%

Controlling the Flow of Energy: Inhibition and Stimulation of the Creatine Transporter

Balestrino¹,

Perasso

2009

CEI

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Creatine in its free and phosphorylated form plays an essential role for maintenance and distribution of ATP levels in tissues with high and fluctuating energy demands such as muscle, brain and heart. Alterations in the creatine concentration in these tissues produce marked functional changes. Creatine concentration is largely determined by a specific creatine transporter, a member of the Na+ dependent transporters family, that is localized on the cells' plasma membrane.This transporter is needed to carry creatine into the cells against a high concentration gradient. In recent years the mechanisms regulating the expression and the function of this transporter are being unraveled. Even if our knowledge of this matter is still limited, we have now tools for either stimulating or inhibiting this transporter, tools that may be relevant to several experimental and clinical conditions. This review will examine the data and the tools that are available in relation to the regulation and expression of the creatine transporter. Furthermore, we will briefly review the possible practical relevance of manipulating the creatine transporter activity.

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Effect of Insulin on the Uptake of Creatine-1-14C by Skeletal Muscle in Normal and X-Irradiated Rats

Cited by 36 publications

References 6 publications

Effects of 30 days of creatine ingestion in older men

Effects of 30 days of creatine ingestion in older men

Resistência à insulina com a suplementação de creatina em animais de experimentação

Controlling the Flow of Energy: Inhibition and Stimulation of the Creatine Transporter

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