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Development of an anaesthetized‐rat model of exercise hyperpnoea: an integrative model of respiratory control using an equilibrium diagram
Author(s) -
Miyamoto Tadayoshi,
Manabe Kou,
Ueda Shinya,
Nakahara Hidehiro
Publication year - 2018
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/ep086850
Subject(s) - cardiorespiratory fitness , respiratory system , respiratory compensation , respiratory physiology , medicine , respiration , ventilation (architecture) , physical medicine and rehabilitation , cardiology , physical therapy , anatomy , physics , anaerobic exercise , thermodynamics
New FindingsWhat is the central question of this study? The lack of useful small‐animal models for studying exercise hyperpnoea makes it difficult to investigate the underlying mechanisms of exercise‐induced ventilatory abnormalities in various disease states.What is the main finding and its importance? We developed an anaesthetized‐rat model for studying exercise hyperpnoea, using a respiratory equilibrium diagram for quantitative characterization of the respiratory chemoreflex feedback system. This experimental model will provide an opportunity to clarify the major determinant mechanisms of exercise hyperpnoea, and will be useful for understanding the mechanisms responsible for abnormal ventilatory responses to exercise in disease models.Abstract Exercise‐induced ventilatory abnormalities in various disease states seem to arise from pathological changes of respiratory regulation. Although experimental studies in small animals are essential to investigate the pathophysiological basis of various disease models, the lack of an integrated framework for quantitatively characterizing respiratory regulation during exercise prevents us from resolving these problems. The purpose of this study was to develop an anaesthetized‐rat model for studying exercise hyperpnoea for quantitative characterization of the respiratory chemoreflex feedback system. In 24 anaesthetized rats, we induced muscle contraction by stimulating bilateral distal sciatic nerves at low and high voltage to mimic exercise. We recorded breath‐by‐breath respiratory gas analysis data and cardiorespiratory responses while running two protocols to characterize the controller and plant of the respiratory chemoreflex. The controller was characterized by determining the linear relationship between end‐tidal CO 2 pressure ( P ETC O 2) and minute ventilation ( V ̇ E ), and the plant by the hyperbolic relationship betweenV ̇ E and P ETC O 2. During exercise, the controller curve shifted upward without change in controller gain, accompanying increased oxygen uptake. The hyperbolic plant curve shifted rightward and downward depending on exercise intensity as predicted by increased metabolism. Exercise intensity‐dependent changes in operating points ( V ̇ E and P ETC O 2) were estimated by integrating the controller and plant curves in a respiratory equilibrium diagram. In conclusion, we developed an anaesthetized‐rat model for studying exercise hyperpnoea, using systems analysis for quantitative characterization of the respiratory system. This novel experimental model will be useful for understanding the mechanisms responsible for abnormal ventilatory responses to exercise in disease models.