| Interstitial pH, K(+), lactate, and phosphate determined with MSNA during exercise in humans. | |
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MedLine Citation:
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PMID: 10712273 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The purpose of the present study was to use the microdialysis technique to simultaneously measure the interstitial concentrations of several putative stimulators of the exercise pressor reflex during 5 min of intermittent static quadriceps exercise in humans (n = 7). Exercise resulted in approximately a threefold (P < 0.05) increase in muscle sympathetic nerve activity (MSNA) and 13 +/- 3 beats/min (P < 0.05) and 20 +/- 2 mmHg (P < 0.05) increases in heart rate and blood pressure, respectively. During recovery, all reflex responses quickly returned to baseline. Interstitial lactate levels were increased (P < 0.05) from rest (1.1 +/- 0.1 mM) to exercise (1. 6 +/- 0.2 mM) and were further increased (P < 0.05) during recovery (2.0 +/- 0.2 mM). Dialysate phosphate concentrations were 0.55 +/- 0. 04, 0.71 +/- 0.05, and 0.48 +/- 0.03 mM during rest, exercise, and recovery, respectively, and were significantly elevated during exercise. At the onset of exercise, dialysate K(+) levels rose rapidly above resting values (4.2 +/- 0.1 meq/l) and continued to increase during the exercise bout. After 5 min of contractions, dialysate K(+) levels had peaked with an increase (P < 0.05) of 0.6 +/- 0.1 meq/l and subsequently decreased during recovery, not being different from rest after 3 min. In contrast, H(+) concentrations rapidly decreased (P < 0.05) from resting levels (69.4 +/- 3.7 nM) during quadriceps exercise and continued to decrease with a mean decline (P < 0.05) of 16.7 +/- 3.8 nM being achieved after 5 min. During recovery, H(+) concentrations rapidly increased and were not significantly different from baseline after 1 min. This study represents the first time that skeletal muscle interstitial pH, K(+), lactate, and phosphate have been measured in conjunction with MSNA, heart rate, and blood pressure during intermittent static quadriceps exercise in humans. These data suggest that interstitial K(+) and phosphate, but not lactate and H(+), may contribute to the stimulation of the exercise pressor reflex. |
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Authors:
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D A MacLean; V A Imadojemu; L I Sinoway |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: American journal of physiology. Regulatory, integrative and comparative physiology Volume: 278 ISSN: 0363-6119 ISO Abbreviation: Am. J. Physiol. Regul. Integr. Comp. Physiol. Publication Date: 2000 Mar |
Date Detail:
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Created Date: 2000-06-20 Completed Date: 2000-06-20 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 100901230 Medline TA: Am J Physiol Regul Integr Comp Physiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: R563-71 Citation Subset: IM; S |
Affiliation:
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Department of Medicine, Section of Cardiology, Allergy and Critical Care, Pennsylvania State University College of Medicine, The Milton S. Hershey Medical Center, Hershey, PA 17033, USA. dmaclean@med.hmc.psghs.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Exercise / physiology* Humans Hydrogen-Ion Concentration Lactic Acid / metabolism* Male Muscle Contraction Muscle, Skeletal / innervation*, physiology* Phosphates / metabolism* Potassium / physiology* Sympathetic Nervous System / physiology* |
| Grant Support | |
ID/Acronym/Agency:
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M01 RR-10732/RR/NCRR NIH HHS; R01 AG-12227/AG/NIA NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Phosphates; 50-21-5/Lactic Acid; 7440-09-7/Potassium |
| Investigator | |
Investigator/Affiliation:
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L I Sinoway / Milton S Hershey Med Ctr, Hershey, PA |
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