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Glycine propionyl-L-carnitine increases plasma nitrate/nitrite in resistance trained men.

Bloomer RJ, Smith WA, Fisher-Wellman KH - J Int Soc Sports Nutr (2007)

Bottom Line: A condition main effect (p = 0.0008) was noted for NOx, with higher values in subjects when using GPLC (45.6 +/- 2.8 mumol.L-1) compared to placebo (34.9 +/- 1.2 mumol.L-1).No time main effect was noted (p = 0.7099), although values increased approximately 12% from rest (37.7 +/- 2.7 mumol.L-1) to a peak at 10 minutes post protocol (42.3 +/- 3.3 mumol.L-1).The interaction effect was not significant (p = 0.8809), although paired time contrasts revealed higher values for GPLC compared to placebo at 3 (48.2 +/- 6.7 vs. 34.9 +/- 2.4 mumol.L-1; p = 0.033) and 10 (48.8 +/- 5.9 vs. 35.7 +/- 2.1 mumol.L-1; p = 0.036) minutes post protocol, with non-statistically significant differences noted at rest (41.8 +/- 4.5 vs. 33.6 +/- 2.5 mumol.L-1; p = 0.189) and at 0 minutes (43.6 +/- 5.1 vs. 35.4 +/- 2.7 mumol.L-1; p = 0.187) post protocol.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Health and Sport Sciences, University of Memphis, Memphis, TN, USA. rbloomer@memphis.edu.

ABSTRACT

Unlabelled: : We have recently demonstrated that oral intake of glycine propionyl-L-carnitine (GPLC) increases plasma nitrate/nitrite (NOx), a surrogate measure of nitric oxide production. However, these findings were observed at rest, and in previously sedentary subjects.

Purpose: In the present study, we sought to determine the impact of oral GPLC on plasma NOx at rest and in response to a period of reactive hyperemia in resistance trained men.

Methods: Using a double blind, crossover design, 15 healthy men (24 +/- 4 years) were assigned to GPLC (3 g/d PLC + 1044 mg glycine) and a placebo in random order, for a four-week period, with a two-week washout between condition assignment. Blood samples were taken from subjects at rest and at 0, 3, and 10 minutes following an ischemia-reperfusion protocol (six minutes of upper arm cuff occlusion at 200 mmHg followed by rapid reperfusion with cuff removal). Blood samples were taken from a forearm vein from the same arm used for the protocol and analyzed for total nitrate/nitrite. Data are presented as mean +/- SEM.

Results: A condition main effect (p = 0.0008) was noted for NOx, with higher values in subjects when using GPLC (45.6 +/- 2.8 mumol.L-1) compared to placebo (34.9 +/- 1.2 mumol.L-1). No time main effect was noted (p = 0.7099), although values increased approximately 12% from rest (37.7 +/- 2.7 mumol.L-1) to a peak at 10 minutes post protocol (42.3 +/- 3.3 mumol.L-1). The interaction effect was not significant (p = 0.8809), although paired time contrasts revealed higher values for GPLC compared to placebo at 3 (48.2 +/- 6.7 vs. 34.9 +/- 2.4 mumol.L-1; p = 0.033) and 10 (48.8 +/- 5.9 vs. 35.7 +/- 2.1 mumol.L-1; p = 0.036) minutes post protocol, with non-statistically significant differences noted at rest (41.8 +/- 4.5 vs. 33.6 +/- 2.5 mumol.L-1; p = 0.189) and at 0 minutes (43.6 +/- 5.1 vs. 35.4 +/- 2.7 mumol.L-1; p = 0.187) post protocol. An analysis by subject (collapsed across time) indicated that 11 of the 15 subjects experienced an increase in NOx with GPLC treatment.

Conclusion: These findings indicate that short-term oral GPLC supplementation can increase NOx in resistance trained men. However, as with many dietary supplements, there exist both "responders" and "non-responders" to treatment. Future work may focus on the mechanisms for the discrepancy in response to GPLC supplementation for purposes of NOx elevation.

No MeSH data available.


Related in: MedlinePlus

Individual subject data for plasma nitrate/nitrite before and after an ischemia-reperfusion protocol in 15 resistance trained men supplemented with GPLC and placebo in a cross-over design. Note: NOx data collapsed over time.
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Figure 2: Individual subject data for plasma nitrate/nitrite before and after an ischemia-reperfusion protocol in 15 resistance trained men supplemented with GPLC and placebo in a cross-over design. Note: NOx data collapsed over time.

Mentions: A condition main effect (p = 0.0008) was noted for NOx, with higher values in subjects when using GPLC (45.6 ± 2.8 μmol·L-1) compared to placebo (34.9 ± 1.2 μmol·L-1). No time main effect was noted for NOx (p = 0.7099), although values increased approximately 12% from rest to a peak at 10 minutes post protocol. The interaction effect for NOx was not significant (p = 0.8809), although paired time contrasts revealed higher values for GPLC compared to placebo at 3 (p = 0.033) and 10 (p = 0.036) minutes post protocol. The interaction data for NOx are presented in Figure 1. An analysis by subject (collapsed across time) indicated that 11 of the 15 subjects experienced an increase in NOx with GPLC treatment (Figure 2).


Glycine propionyl-L-carnitine increases plasma nitrate/nitrite in resistance trained men.

Bloomer RJ, Smith WA, Fisher-Wellman KH - J Int Soc Sports Nutr (2007)

Individual subject data for plasma nitrate/nitrite before and after an ischemia-reperfusion protocol in 15 resistance trained men supplemented with GPLC and placebo in a cross-over design. Note: NOx data collapsed over time.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2211291&req=5

Figure 2: Individual subject data for plasma nitrate/nitrite before and after an ischemia-reperfusion protocol in 15 resistance trained men supplemented with GPLC and placebo in a cross-over design. Note: NOx data collapsed over time.
Mentions: A condition main effect (p = 0.0008) was noted for NOx, with higher values in subjects when using GPLC (45.6 ± 2.8 μmol·L-1) compared to placebo (34.9 ± 1.2 μmol·L-1). No time main effect was noted for NOx (p = 0.7099), although values increased approximately 12% from rest to a peak at 10 minutes post protocol. The interaction effect for NOx was not significant (p = 0.8809), although paired time contrasts revealed higher values for GPLC compared to placebo at 3 (p = 0.033) and 10 (p = 0.036) minutes post protocol. The interaction data for NOx are presented in Figure 1. An analysis by subject (collapsed across time) indicated that 11 of the 15 subjects experienced an increase in NOx with GPLC treatment (Figure 2).

Bottom Line: A condition main effect (p = 0.0008) was noted for NOx, with higher values in subjects when using GPLC (45.6 +/- 2.8 mumol.L-1) compared to placebo (34.9 +/- 1.2 mumol.L-1).No time main effect was noted (p = 0.7099), although values increased approximately 12% from rest (37.7 +/- 2.7 mumol.L-1) to a peak at 10 minutes post protocol (42.3 +/- 3.3 mumol.L-1).The interaction effect was not significant (p = 0.8809), although paired time contrasts revealed higher values for GPLC compared to placebo at 3 (48.2 +/- 6.7 vs. 34.9 +/- 2.4 mumol.L-1; p = 0.033) and 10 (48.8 +/- 5.9 vs. 35.7 +/- 2.1 mumol.L-1; p = 0.036) minutes post protocol, with non-statistically significant differences noted at rest (41.8 +/- 4.5 vs. 33.6 +/- 2.5 mumol.L-1; p = 0.189) and at 0 minutes (43.6 +/- 5.1 vs. 35.4 +/- 2.7 mumol.L-1; p = 0.187) post protocol.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Health and Sport Sciences, University of Memphis, Memphis, TN, USA. rbloomer@memphis.edu.

ABSTRACT

Unlabelled: : We have recently demonstrated that oral intake of glycine propionyl-L-carnitine (GPLC) increases plasma nitrate/nitrite (NOx), a surrogate measure of nitric oxide production. However, these findings were observed at rest, and in previously sedentary subjects.

Purpose: In the present study, we sought to determine the impact of oral GPLC on plasma NOx at rest and in response to a period of reactive hyperemia in resistance trained men.

Methods: Using a double blind, crossover design, 15 healthy men (24 +/- 4 years) were assigned to GPLC (3 g/d PLC + 1044 mg glycine) and a placebo in random order, for a four-week period, with a two-week washout between condition assignment. Blood samples were taken from subjects at rest and at 0, 3, and 10 minutes following an ischemia-reperfusion protocol (six minutes of upper arm cuff occlusion at 200 mmHg followed by rapid reperfusion with cuff removal). Blood samples were taken from a forearm vein from the same arm used for the protocol and analyzed for total nitrate/nitrite. Data are presented as mean +/- SEM.

Results: A condition main effect (p = 0.0008) was noted for NOx, with higher values in subjects when using GPLC (45.6 +/- 2.8 mumol.L-1) compared to placebo (34.9 +/- 1.2 mumol.L-1). No time main effect was noted (p = 0.7099), although values increased approximately 12% from rest (37.7 +/- 2.7 mumol.L-1) to a peak at 10 minutes post protocol (42.3 +/- 3.3 mumol.L-1). The interaction effect was not significant (p = 0.8809), although paired time contrasts revealed higher values for GPLC compared to placebo at 3 (48.2 +/- 6.7 vs. 34.9 +/- 2.4 mumol.L-1; p = 0.033) and 10 (48.8 +/- 5.9 vs. 35.7 +/- 2.1 mumol.L-1; p = 0.036) minutes post protocol, with non-statistically significant differences noted at rest (41.8 +/- 4.5 vs. 33.6 +/- 2.5 mumol.L-1; p = 0.189) and at 0 minutes (43.6 +/- 5.1 vs. 35.4 +/- 2.7 mumol.L-1; p = 0.187) post protocol. An analysis by subject (collapsed across time) indicated that 11 of the 15 subjects experienced an increase in NOx with GPLC treatment.

Conclusion: These findings indicate that short-term oral GPLC supplementation can increase NOx in resistance trained men. However, as with many dietary supplements, there exist both "responders" and "non-responders" to treatment. Future work may focus on the mechanisms for the discrepancy in response to GPLC supplementation for purposes of NOx elevation.

No MeSH data available.


Related in: MedlinePlus