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Published on: April 23, 2018
Exercise pressor reflex in decerebrate and anesthetized rats
1Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis 95616, USA. naohayashi@ans.hss.osaka-u.ac.jp
American Journal of Physiology. Heart and Circulatory Physiology
|January 25, 2003
Summary
The midcollicular decerebrated rat model effectively demonstrates the exercise pressor reflex, showing significant increases in blood pressure, heart rate, and ventilation during muscle contraction.
Area of Science:
- Cardiovascular Physiology
- Neuroscience
- Exercise Physiology
Background:
- The exercise pressor reflex (EPR) is a crucial mechanism regulating cardiorespiratory function during physical activity.
- Understanding the neural pathways involved in EPR is essential for comprehending physiological responses to exercise.
Purpose of the Study:
- To investigate the efficacy of different rat preparations in modeling the exercise pressor reflex.
- To identify a suitable animal model for studying the neural control of cardiorespiratory responses during muscle contraction.
Main Methods:
- Experiments were conducted on rats under alpha-chloralose/chloral hydrate anesthesia and various decerebration levels (precollicular, midcollicular, postcollicular).
- Mean arterial pressure (MAP), heart rate (HR), and minute ventilation (Ve) were measured during sciatic nerve stimulation-induced muscle contraction and tendon stretch.
- Responses were analyzed in intact, paralyzed, and decerebrated preparations to isolate the EPR.
Main Results:
- Anesthetized rats exhibited variable MAP responses to stimuli.
- Precollicular decerebrated rats showed spontaneous running, confounding EPR assessment.
- Postcollicular decerebrated rats did not display EPR.
- Midcollicular decerebrated rats consistently showed a biphasic MAP response, with significant increases in MAP, HR, and Ve during static muscle contraction (381 +/- 65 g tension).
- Paralysis abolished the cardiorespiratory responses to nerve stimulation, confirming a reflex mechanism.
Conclusions:
- The midcollicular decerebrated rat preparation is a viable and reliable model for studying the exercise pressor reflex.
- This model allows for the isolation and investigation of the neural control of cardiorespiratory adjustments during exercise without confounding factors like anesthesia or higher brain centers.
