Related Experiment Videos
Reflex effects on circulation and respiration from contracting skeletal muscle
The American Journal of Physiology
|September 1, 1977
Summary
Isometric exercise in cats reflexly increases heart rate, blood pressure, and respiratory volume via skeletal muscle afferents. Beta-adrenergic blockade partially affects these cardiovascular responses.
Area of Science:
- Cardiovascular Physiology
- Exercise Physiology
- Neuroscience
Background:
- Isometric exercise elicits reflex cardiovascular and respiratory adjustments.
- The neural pathways and mechanisms mediating these responses are not fully elucidated.
Purpose of the Study:
- To investigate the reflex cardiovascular and respiratory effects of isometric exercise.
- To determine the role of skeletal muscle afferents and beta-adrenergic receptors in these responses.
Main Methods:
- Isometric exercise was induced via ventral root stimulation in anesthetized cats.
- Measurements included heart rate, mean arterial pressure, left ventricular dp/dt, and respiratory volume.
- Dorsal roots were sectioned, and beta-adrenergic blockade was administered using propranolol.
Main Results:
- Isometric exercise significantly increased heart rate, mean arterial pressure, left ventricular contractility, and respiratory volume.
- Sectioning dorsal roots abolished these changes, indicating a reflex origin from skeletal muscle.
- Beta-adrenergic blockade attenuated heart rate and contractility changes but not those in mean arterial pressure and respiratory volume.
Conclusions:
- Isometric exercise induces reflex cardiovascular and respiratory changes originating from contracting skeletal muscle.
- Both neural reflexes and beta-adrenergic mechanisms contribute to the cardiovascular adjustments during isometric exercise.