Document Detail

MCA Vmean and the arterial lactate-to-pyruvate ratio correlate during rhythmic handgrip.
MedLine Citation:
PMID:  16794025     Owner:  NLM     Status:  MEDLINE    
Regulation of cerebral blood flow during physiological activation including exercise remains unknown but may be related to the arterial lactate-to-pyruvate (L/P) ratio. We evaluated whether an exercise-induced increase in middle cerebral artery mean velocity (MCA Vmean) relates to the arterial L/P ratio at two plasma lactate levels. MCA Vmean was determined by ultrasound Doppler sonography at rest, during 10 min of rhythmic handgrip exercise at approximately 65% of maximal voluntary contraction force, and during 20 min of recovery in seven healthy male volunteers during control and a approximately 15 mmol/l hyperglycemic clamp. Cerebral arteriovenous differences for metabolites were obtained by brachial artery and retrograde jugular venous catheterization. Control resting arterial lactate was 0.78 +/- 0.09 mmol/l (mean +/- SE) and pyruvate 55.7 +/- 12.0 micromol/l (L/P ratio 16.4 +/- 1.0) with a corresponding MCA Vmean of 46.7 +/- 4.5 cm/s. During rhythmic handgrip the increase in MCA Vmean to 51.2 +/- 4.6 cm/s was related to the increased L/P ratio (23.8 +/- 2.5; r2 = 0.79; P < 0.01). Hyperglycemia increased arterial lactate and pyruvate to 1.9 +/- 0.2 mmol/l and 115 +/- 4 micromol/l, respectively, but it did not significantly influence the L/P ratio or MCA Vmean at rest or during exercise. Conversely, MCA Vmean did not correlate significantly, neither to the arterial lactate nor to the pyruvate concentrations. These results support that the arterial plasma L/P ratio modulates cerebral blood flow during cerebral activation independently from the plasma glucose concentration.
Peter Rasmussen; Peter Plomgaard; Rikke Krogh-Madsen; Yu-Sok Kim; Johannes J van Lieshout; Niels H Secher; Bjørn Quistorff
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-06-22
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  101     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2006 Nov 
Date Detail:
Created Date:  2006-10-17     Completed Date:  2006-11-28     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1406-11     Citation Subset:  IM    
Deapartment of Anesthesia, Copenhagen Muscle Center, University of Copenhagen, Denmark.
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MeSH Terms
Blood Flow Velocity / physiology
Blood Pressure / physiology
Brain / blood supply*
Cerebrovascular Circulation / physiology
Exercise / physiology*
Glucose Clamp Technique
Hand Strength / physiology*
Heart Rate / physiology
Hyperglycemia / blood,  physiopathology
Lactic Acid / blood*
Middle Cerebral Artery / physiology*,  ultrasonography
Pyruvic Acid / blood*
Ultrasonography, Doppler, Transcranial
Reg. No./Substance:
127-17-3/Pyruvic Acid; 50-21-5/Lactic Acid

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