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Nitric oxide synthase inhibition speeds oxygen uptake kinetics in horses during moderate domain running.
Abstract: Within the moderate exercise intensity domain, the speed of oxygen uptake (V(O(2))) kinetics at the transition to a higher metabolic rate is thought to be limited by an inertia of the oxidative machinery. Nitric oxide (NO)-induced inhibition of O(2) consumption within the electron transport chain may contribute to this inertia. This investigation tested the hypothesis that a reduction or removal of any such NO effect via infusion of N(omega)-nitro-L-arginine methyl ester (L-NAME; a NOS inhibitor) would speed V(O(2)) kinetics at the onset of moderate exercise. Five Thoroughbred geldings underwent four transitions to running speeds of 7 m sec(-1) (two control, C, 2 L-NAME [20 mg kg(-1)]) on an equine treadmill during which pulmonary gas exchange was determined using a bias flow system. Consistent with exercise in the moderate intensity domain, in none of the transitions was a V(O(2)) slow component elicited. The L-NAME treatment significantly accelerated V(O(2)) kinetics via a reduction of the primary amplitude time constant (C, 17.3 +/- 1.7; L-NAME, 11.8 +/- 1.5 sec, P < 0.05) concomitant with faster overall dynamics (i.e. T(50) and T(75) both P < 0.05) and a trend toward a decreased O(2) deficit (C, 6.4 +/- 0.7; L-NAME, 4.7 +/- 1.2 L; P = 0.06). These data support the notion that NO contributes prominently to the oxidative enzyme inertia and thus the speed of V(O(2)) kinetics at the onset of moderate intensity exercise in the horse.
Publication Date: 2002-08-06 PubMed ID: 12161330DOI: 10.1016/s1569-9048(02)00068-xGoogle 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
- 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.
This research investigates whether inhibiting Nitric oxide synthase (NOS), an enzyme responsible for nitric oxide production, can speed up the uptake of oxygen in horses during moderate-intensity exercise. The study results indicate that blocking nitric oxide production through the introduction of N(omega)-nitro-L-arginine methyl ester (L-NAME) increases the speed of oxygen uptake, which suggests a significant role of nitric oxide in controlling the rate of oxygen consumption under these conditions.
Understanding Nitric Oxide (NO) and Oxygen Uptake Kinetics
- Nitric oxide (NO) contributes significantly to the inertia of oxidative machinery, causing a delay in the onset of oxygen consumption (V(O(2))) as the metabolic rate increases during moderate exercise intensity.
- Oxygen uptake kinetics refer to how quickly the body can absorb and utilize oxygen, particularly during physical activity. Faster V(O(2)) kinetics enable quicker adaptation to exercise.
Experimental Design and Execution
- The experiment involved five Thoroughbred geldings that underwent four transitions to a running speed of 7 m per second, including two control phases and two phases involving the introduction of L-NAME, an NOS inhibitor.
- The pulmonary gas exchanges of the horses were monitored using a bias flow system across these different phases. The transitions did not result in a V(O(2)) slow component, indicating that the exercise was kept within the moderate intensity domain.
Significant Findings
- Introduction of L-NAME significantly expedited V(O(2)) kinetics — the rate at which the horse’s body absorbed and utilized oxygen. This was evidenced by a reduction in the primary amplitude time constant and faster overall dynamics for oxygen uptake.
- The study also observed a trend towards a decreased oxygen deficit with the L-NAME treatment, although this was not significant at the P < 0.05 level.
Implications
- The experiment underscores the prominent role played by NO in oxygen uptake kinetics during moderate intensity exercise.
- The findings could potentially lead to the development of new strategies for enhancing athletic performance in horses and other large animals by manipulating NO levels.
Cite This Article
APA
Kindig CA, McDonough P, Erickson HH, Poole DC.
(2002).
Nitric oxide synthase inhibition speeds oxygen uptake kinetics in horses during moderate domain running.
Respir Physiol Neurobiol, 132(2), 169-178.
https://doi.org/10.1016/s1569-9048(02)00068-x Publication
Researcher Affiliations
- Department of Anatomy, Kansas State University, 228 Coles Hall, 1600 Denison Avenue Manhattan, KS 66506-5802, USA. ckindig@ucsd.edu
MeSH Terms
- Analysis of Variance
- Animals
- Enzyme Inhibitors / pharmacology
- Exercise Test
- Horses / physiology
- Lactic Acid / blood
- Male
- Matched-Pair Analysis
- NG-Nitroarginine Methyl Ester / pharmacology
- Nitric Oxide Synthase / antagonists & inhibitors
- Oxygen / pharmacokinetics
- Oxygen Consumption / drug effects
- Respiration / drug effects
- Running / physiology
Grant Funding
- HL-50306 / NHLBI NIH HHS
Citations
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