Plasma pH does not influence the cerebral metabolic ratio during maximal whole body exercise

Stefanos Volianitis; Peter Rasmussen; Thomas Seifert; H B Nielsen; N H Secher

doi:10.1113/jphysiol.2010.195636

Plasma pH does not influence the cerebral metabolic ratio during maximal whole body exercise

Stefanos Volianitis, Peter Rasmussen, Thomas Seifert, H B Nielsen, N H Secher

11 Citations (Scopus)

Abstract

Non-technical summary: Exercise is known to promote the use of lactate as metabolic fuel for the brain. As a result the cerebral metabolic ratio, an index of the brain's metabolism, is reduced compared to rest. It is not known whether the exercise-induced metabolic acidosis affects cerebral metabolism and the reduction of the cerebral metabolic ratio. We manipulated the metabolic acidosis by infusing bicarbonate in well trained rowers during a maximal rowing ergometer effort. We show that elimination of acidosis does not affect the reduction of the cerebral metabolic ratio. Furthermore, the data indicate that the capacity of the brain to take up lactate may have a limit. This indication requires further evaluation.Abstract Exercise lowers the cerebral metabolic ratio of O₂ to carbohydrate (glucose + 1/2 lactate) and metabolic acidosis appears to promote cerebral lactate uptake. However, the influence of pH on cerebral lactate uptake and, in turn, on the cerebral metabolic ratio during exercise is not known. Sodium bicarbonate (Bicarb, 1 m; 350-500 ml) or an equal volume of normal saline (Sal) was infused intravenously at a constant rate during a '2000 m' maximal ergometer row in six male oarsmen (23 ± 2 years; mean ±s.d.). During the Sal trial, pH decreased from 7.41 ± 0.01 at rest to 7.02 ± 0.02 but only to 7.36 ± 0.02 (P < 0.05) during the Bicarb trial. Arterial lactate increased to 21.4 ± 0.8 and 32.7 ± 2.3 mm during the Sal and Bicarb trials, respectively (P < 0.05). Also, the arterial-jugular venous lactate difference increased from -0.03 ± 0.01 mm at rest to 3.2 ± 0.9 mm (P < 0.05) and 3.4 ± 1.4 mm (P < 0.05) following the Sal and Bicarb trials, respectively. Accordingly, the cerebral metabolic ratio decreased equally during the Sal and Bicarb trials: from 5.8 ± 0.6 at rest to 1.7 ± 0.1 and 1.8 ± 0.2, respectively. The enlarged blood-buffering capacity after infusion of Bicarb eliminated metabolic acidosis during maximal exercise but that did not affect the cerebral lactate uptake and, therefore, the decrease in the cerebral metabolic ratio.Exercise is known to promote the use of lactate as metabolic fuel for the brain. As a result the cerebral metabolic ratio, an index of the brain's metabolism, is reduced compared to rest. It is not known whether the exercise-induced metabolic acidosis affects cerebral metabolism and the reduction of the cerebral metabolic ratio. We manipulated the metabolic acidosis by infusing bicarbonate in well trained rowers during a maximal rowing ergometer effort. We show that elimination of acidosis does not affect the reduction of the cerebral metabolic ratio. Furthermore, the data indicate that the capacity of the brain to take up lactate may have a limit. This indication requires further evaluation.

Original language	English
Journal	Journal of Physiology
Volume	589
Issue number	Pt 2
Pages (from-to)	423-9
Number of pages	7
ISSN	0022-3751
DOIs	https://doi.org/10.1113/jphysiol.2010.195636
Publication status	Published - 15 Jan 2011

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@article{ab4dbaec6d6f45d0bd4852c7202493a4,

title = "Plasma pH does not influence the cerebral metabolic ratio during maximal whole body exercise",

abstract = "Non-technical summary: Exercise is known to promote the use of lactate as metabolic fuel for the brain. As a result the cerebral metabolic ratio, an index of the brain's metabolism, is reduced compared to rest. It is not known whether the exercise-induced metabolic acidosis affects cerebral metabolism and the reduction of the cerebral metabolic ratio. We manipulated the metabolic acidosis by infusing bicarbonate in well trained rowers during a maximal rowing ergometer effort. We show that elimination of acidosis does not affect the reduction of the cerebral metabolic ratio. Furthermore, the data indicate that the capacity of the brain to take up lactate may have a limit. This indication requires further evaluation.Abstract Exercise lowers the cerebral metabolic ratio of O2 to carbohydrate (glucose + 1/2 lactate) and metabolic acidosis appears to promote cerebral lactate uptake. However, the influence of pH on cerebral lactate uptake and, in turn, on the cerebral metabolic ratio during exercise is not known. Sodium bicarbonate (Bicarb, 1 m; 350-500 ml) or an equal volume of normal saline (Sal) was infused intravenously at a constant rate during a '2000 m' maximal ergometer row in six male oarsmen (23 ± 2 years; mean ±s.d.). During the Sal trial, pH decreased from 7.41 ± 0.01 at rest to 7.02 ± 0.02 but only to 7.36 ± 0.02 (P < 0.05) during the Bicarb trial. Arterial lactate increased to 21.4 ± 0.8 and 32.7 ± 2.3 mm during the Sal and Bicarb trials, respectively (P < 0.05). Also, the arterial-jugular venous lactate difference increased from -0.03 ± 0.01 mm at rest to 3.2 ± 0.9 mm (P < 0.05) and 3.4 ± 1.4 mm (P < 0.05) following the Sal and Bicarb trials, respectively. Accordingly, the cerebral metabolic ratio decreased equally during the Sal and Bicarb trials: from 5.8 ± 0.6 at rest to 1.7 ± 0.1 and 1.8 ± 0.2, respectively. The enlarged blood-buffering capacity after infusion of Bicarb eliminated metabolic acidosis during maximal exercise but that did not affect the cerebral lactate uptake and, therefore, the decrease in the cerebral metabolic ratio.Exercise is known to promote the use of lactate as metabolic fuel for the brain. As a result the cerebral metabolic ratio, an index of the brain's metabolism, is reduced compared to rest. It is not known whether the exercise-induced metabolic acidosis affects cerebral metabolism and the reduction of the cerebral metabolic ratio. We manipulated the metabolic acidosis by infusing bicarbonate in well trained rowers during a maximal rowing ergometer effort. We show that elimination of acidosis does not affect the reduction of the cerebral metabolic ratio. Furthermore, the data indicate that the capacity of the brain to take up lactate may have a limit. This indication requires further evaluation.",

author = "Stefanos Volianitis and Peter Rasmussen and Thomas Seifert and Nielsen, {H B} and Secher, {N H}",

year = "2011",

month = jan,

day = "15",

doi = "10.1113/jphysiol.2010.195636",

language = "English",

volume = "589",

pages = "423--9",

journal = "Journal of Physiology",

issn = "0022-3751",

publisher = "Wiley-Blackwell",

number = "Pt 2",

}

TY - JOUR

T1 - Plasma pH does not influence the cerebral metabolic ratio during maximal whole body exercise

AU - Volianitis, Stefanos

AU - Rasmussen, Peter

AU - Seifert, Thomas

AU - Nielsen, H B

AU - Secher, N H

PY - 2011/1/15

Y1 - 2011/1/15

N2 - Non-technical summary: Exercise is known to promote the use of lactate as metabolic fuel for the brain. As a result the cerebral metabolic ratio, an index of the brain's metabolism, is reduced compared to rest. It is not known whether the exercise-induced metabolic acidosis affects cerebral metabolism and the reduction of the cerebral metabolic ratio. We manipulated the metabolic acidosis by infusing bicarbonate in well trained rowers during a maximal rowing ergometer effort. We show that elimination of acidosis does not affect the reduction of the cerebral metabolic ratio. Furthermore, the data indicate that the capacity of the brain to take up lactate may have a limit. This indication requires further evaluation.Abstract Exercise lowers the cerebral metabolic ratio of O2 to carbohydrate (glucose + 1/2 lactate) and metabolic acidosis appears to promote cerebral lactate uptake. However, the influence of pH on cerebral lactate uptake and, in turn, on the cerebral metabolic ratio during exercise is not known. Sodium bicarbonate (Bicarb, 1 m; 350-500 ml) or an equal volume of normal saline (Sal) was infused intravenously at a constant rate during a '2000 m' maximal ergometer row in six male oarsmen (23 ± 2 years; mean ±s.d.). During the Sal trial, pH decreased from 7.41 ± 0.01 at rest to 7.02 ± 0.02 but only to 7.36 ± 0.02 (P < 0.05) during the Bicarb trial. Arterial lactate increased to 21.4 ± 0.8 and 32.7 ± 2.3 mm during the Sal and Bicarb trials, respectively (P < 0.05). Also, the arterial-jugular venous lactate difference increased from -0.03 ± 0.01 mm at rest to 3.2 ± 0.9 mm (P < 0.05) and 3.4 ± 1.4 mm (P < 0.05) following the Sal and Bicarb trials, respectively. Accordingly, the cerebral metabolic ratio decreased equally during the Sal and Bicarb trials: from 5.8 ± 0.6 at rest to 1.7 ± 0.1 and 1.8 ± 0.2, respectively. The enlarged blood-buffering capacity after infusion of Bicarb eliminated metabolic acidosis during maximal exercise but that did not affect the cerebral lactate uptake and, therefore, the decrease in the cerebral metabolic ratio.Exercise is known to promote the use of lactate as metabolic fuel for the brain. As a result the cerebral metabolic ratio, an index of the brain's metabolism, is reduced compared to rest. It is not known whether the exercise-induced metabolic acidosis affects cerebral metabolism and the reduction of the cerebral metabolic ratio. We manipulated the metabolic acidosis by infusing bicarbonate in well trained rowers during a maximal rowing ergometer effort. We show that elimination of acidosis does not affect the reduction of the cerebral metabolic ratio. Furthermore, the data indicate that the capacity of the brain to take up lactate may have a limit. This indication requires further evaluation.

AB - Non-technical summary: Exercise is known to promote the use of lactate as metabolic fuel for the brain. As a result the cerebral metabolic ratio, an index of the brain's metabolism, is reduced compared to rest. It is not known whether the exercise-induced metabolic acidosis affects cerebral metabolism and the reduction of the cerebral metabolic ratio. We manipulated the metabolic acidosis by infusing bicarbonate in well trained rowers during a maximal rowing ergometer effort. We show that elimination of acidosis does not affect the reduction of the cerebral metabolic ratio. Furthermore, the data indicate that the capacity of the brain to take up lactate may have a limit. This indication requires further evaluation.Abstract Exercise lowers the cerebral metabolic ratio of O2 to carbohydrate (glucose + 1/2 lactate) and metabolic acidosis appears to promote cerebral lactate uptake. However, the influence of pH on cerebral lactate uptake and, in turn, on the cerebral metabolic ratio during exercise is not known. Sodium bicarbonate (Bicarb, 1 m; 350-500 ml) or an equal volume of normal saline (Sal) was infused intravenously at a constant rate during a '2000 m' maximal ergometer row in six male oarsmen (23 ± 2 years; mean ±s.d.). During the Sal trial, pH decreased from 7.41 ± 0.01 at rest to 7.02 ± 0.02 but only to 7.36 ± 0.02 (P < 0.05) during the Bicarb trial. Arterial lactate increased to 21.4 ± 0.8 and 32.7 ± 2.3 mm during the Sal and Bicarb trials, respectively (P < 0.05). Also, the arterial-jugular venous lactate difference increased from -0.03 ± 0.01 mm at rest to 3.2 ± 0.9 mm (P < 0.05) and 3.4 ± 1.4 mm (P < 0.05) following the Sal and Bicarb trials, respectively. Accordingly, the cerebral metabolic ratio decreased equally during the Sal and Bicarb trials: from 5.8 ± 0.6 at rest to 1.7 ± 0.1 and 1.8 ± 0.2, respectively. The enlarged blood-buffering capacity after infusion of Bicarb eliminated metabolic acidosis during maximal exercise but that did not affect the cerebral lactate uptake and, therefore, the decrease in the cerebral metabolic ratio.Exercise is known to promote the use of lactate as metabolic fuel for the brain. As a result the cerebral metabolic ratio, an index of the brain's metabolism, is reduced compared to rest. It is not known whether the exercise-induced metabolic acidosis affects cerebral metabolism and the reduction of the cerebral metabolic ratio. We manipulated the metabolic acidosis by infusing bicarbonate in well trained rowers during a maximal rowing ergometer effort. We show that elimination of acidosis does not affect the reduction of the cerebral metabolic ratio. Furthermore, the data indicate that the capacity of the brain to take up lactate may have a limit. This indication requires further evaluation.

U2 - 10.1113/jphysiol.2010.195636

DO - 10.1113/jphysiol.2010.195636

M3 - Journal article

C2 - 21098003

SN - 0022-3751

VL - 589

SP - 423

EP - 429

JO - Journal of Physiology

JF - Journal of Physiology

IS - Pt 2

ER -

Plasma pH does not influence the cerebral metabolic ratio during maximal whole body exercise

Abstract

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