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Effect of L-NAME on oxygen uptake kinetics during heavy-intensity exercise in the horse.
Abstract: There is evidence that oxidative enzyme inertia plays a major role in limiting/setting the O(2) uptake (VO(2)) response at the transition to higher metabolic rates and also that nitric oxide (NO) competitively inhibits VO(2) within the electron transport chain. To investigate whether NO is important in setting the dynamic response of VO(2) at the onset of high-intensity (heavy-domain) running in horses, five geldings were run on a treadmill across speed transitions from 3 m/s to speeds corresponding to 80% of peak VO(2) with and without nitro-L-arginine methyl ester (L-NAME), an NO synthase inhibitor (20 mg/kg; order randomized). L-NAME did not alter (both P > 0.05) baseline (3 m/s, 15.4 +/- 0.3 and 16.2 +/- 0.5 l/min for control and L-NAME, respectively) or end-exercise VO(2) (56.9 +/- 5.1 and 55.2 +/- 5.8 l/min for control and L-NAME, respectively). However, in the L-NAME trial, the primary on-kinetic response was significantly (P 0.05). The faster on-kinetic response was confirmed independent of modeling by reduced time to 50, 63, and 75% of overall VO(2) response (all P < 0.05). In addition, onset of the VO(2) slow component occurred earlier (124.6 +/- 11.2 and 65.0 +/- 6.6 s for control and L-NAME, respectively), and the magnitude of the O(2) deficit was attenuated (both P < 0.05) in the L-NAME compared with the control trial. Acceleration of the VO(2) kinetics by L-NAME suggests that NO inhibition of mitochondrial VO(2) may contribute, in part, to the intrinsic metabolic inertia evidenced at the transition to higher metabolic rates in the horse.
Publication Date: 2001-07-18 PubMed ID: 11457807DOI: 10.1152/jappl.2001.91.2.891Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- P.H.S.
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The research study aimed to investigate how L-NAME (a nitric oxide synthase inhibitor) affects a horse’s oxygen consumption during high-intensity exercise. It found that although L-NAME did not alter the baseline or end-exercise oxygen uptake, it significantly sped up the primary on-kinetic response, suggesting that the inhibition of mitochondrial oxygen uptake by nitric oxide could be contributing to the metabolic inertia observed when horses transition to higher metabolic rates.
Research Context
- This study focuses on understanding how Nitric Oxide (NO), a gas produced in the body that has several important functions including regulating blood pressure and assisting the immune system, intrinsically affects oxygen uptake.
- The researchers used L-NAME (nitro-L-arginine methyl ester), an inhibitor of Nitric Oxide Synthase (NOS), the enzyme responsible for creating NO in the body.
- The goal was to investigate whether NO plays a significant role in setting the dynamic response of oxygen uptake (VO2) during heavy-intensity exercise in horses.
Experimental Design and Results
- Five geldings (castrated male horses) were made to run on a treadmill at different intensities, with and without the administration of L-NAME.
- The experiments controlled for speed, moving from 3 m/s to speeds that corresponded to 80% of their peak oxygen uptake.
- The study found that L-NAME did not alter either the baseline or end-exercise oxygen uptake levels.
- Despite this, the primary on-kinetic response – the oxygen uptake response triggered at the onset of heavy-intensity running – was significantly faster in the L-NAME trial.
- The onset of the VO2 slow component occurred earlier with L-NAME and the magnitude of the oxygen deficit was also reduced compared to the control trial.
Research implications
- By finding that L-NAME accelerates the VO2 kinetics, the study provides evidence that Nitric Oxide plays a part in the inertia of metabolic responses when a horse transitions to high-intensity exercise.
- Further work is needed to investigate this effect across different species and to further understand the mechanisms by which Nitric Oxide affects VO2 kinetics.
Cite This Article
APA
Kindig CA, McDonough P, Erickson HH, Poole DC.
(2001).
Effect of L-NAME on oxygen uptake kinetics during heavy-intensity exercise in the horse.
J Appl Physiol (1985), 91(2), 891-896.
https://doi.org/10.1152/jappl.2001.91.2.891 Publication
Researcher Affiliations
- Department of Anatomy, Kansas State University, Manhattan, Kansas 66506-5602, USA.
MeSH Terms
- Animals
- Carbon Dioxide / analysis
- Horses
- Kinetics
- Male
- Mass Spectrometry
- NG-Nitroarginine Methyl Ester / pharmacology
- Orchiectomy
- Oxygen / analysis
- Oxygen Consumption / drug effects
- Physical Conditioning, Animal / physiology
- Physical Exertion / drug effects
- Physical Exertion / physiology
- Respiratory Mechanics / physiology
- Time Factors
Grant Funding
- HL-50306 / NHLBI NIH HHS
Citations
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