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Hypergravitation and sympatho-adrenergic reactivity
P Groza1, R Carmaciu, E Nicolescu
1The "D. Danielopolu" Institute of Normal and Pathological Physiology, Bucharest, Rumania.
Life Sciences and Space Research
|January 1, 1976
Summary
Hypergravitation triggers sympatho-adrenergic responses in rats, affecting heart rate and catecholamine levels. Drug interventions like hexamethonium and atropine significantly altered these physiological reactions during acceleration.
Area of Science:
- Physiology
- Aerospace Medicine
- Pharmacology
Background:
- Understanding the physiological response to hypergravitation is crucial for human spaceflight.
- The sympatho-adrenergic system plays a key role in mediating responses to G-force exposure.
- Adrenal catecholamines are critical mediators of the stress response.
Purpose of the Study:
- To investigate the sympatho-adrenergic reaction of rats under hypergravitational stress (+6 Gz).
- To evaluate the effects of hexamethonium and atropine on heart rate and adrenal catecholamine levels during hypergravitation.
Main Methods:
- Rats were exposed to +6 Gz acceleration.
- Telemetric electrocardiograms (ECG) and cardiotachograms were recorded.
- Adrenal catecholamine content was measured.
- Animals were treated with hexamethonium, atropine, or both, separately or together.
Main Results:
- Rats exhibited initial bradycardia followed by tachycardia under +6 Gz.
- Hexamethonium reduced resting heart rate, attenuated initial bradycardia, and decreased subsequent tachycardia.
- Hexamethonium treatment led to increased catecholamine concentration in adrenals.
- Atropine induced resting tachycardia, abolished initial bradycardia, and enhanced tachycardia.
- Combined administration of atropine and hexamethonium diminished the overall response to acceleration.
Conclusions:
- The sympatho-adrenergic system is significantly involved in the cardiovascular response to hypergravitation.
- Hexamethonium and atropine differentially modulate the autonomic response to G-force exposure.
- Pharmacological interventions can alter the physiological impact of hypergravitation, suggesting potential countermeasures.