Maximum oxygen consumption of rats and its changes with various experimental procedures

Area of Science:

• Physiology
• Exercise Science
• Animal Models

Background:

• Maximal oxygen uptake (VO2max) is a key indicator of cardiorespiratory fitness.
• Standardized methods for assessing VO2max in rat models are crucial for research reproducibility.
• Previous studies utilized varied exercise protocols, complicating comparisons.

Purpose of the Study:

• To develop and validate a reliable ten-stage treadmill test for determining rat VO2max.
• To compare VO2max across different rat strains (Sprague-Dawley, WKY, SHR).
• To evaluate the impact of chronic exercise protocols on VO2max and analyze sex-based differences in hypertensive rats.

Main Methods:

• A ten-stage treadmill protocol was developed and validated for reliability.
• VO2max was measured in Sprague-Dawley, Wistar-Kyoto (WKY), and spontaneously hypertensive (SHR) rats.
• Chronic exercise interventions (6-10 weeks) were implemented, and VO2max was reassessed.
• Longitudinal data (1 year) from SHR rats were analyzed using both conventional and logarithmic methods for VO2max and body mass relationships.

Main Results:

• The treadmill test demonstrated high reliability for VO2max measurement.
• Untrained Sprague-Dawley rats exhibited higher VO2max than WKY and SHR rats.
• Chronic exercise (6-10 weeks) led to significant VO2max increases (12-26%).
• Logarithmic analysis revealed sex-based VO2max differences in SHR rats only at 1 year of age, unlike conventional methods.

Conclusions:

• The standardized treadmill test is a reliable tool for VO2max assessment in diverse rat experimental groups.
• Chronic exercise effectively enhances VO2max in rats.
• Logarithmic evaluation of VO2max relative to body mass is recommended for longitudinal studies, especially in hypertensive rat models, to accurately interpret sex-based differences.