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Cardiac output and its distribution during diving in the rat
The American Journal of Physiology
|March 1, 1975
Summary
Rats exhibit a diving response when their heads are submerged, significantly reducing heart rate and cardiac output. This physiological reaction, similar to diving mammals, suggests rats are a valuable model for studying mammalian diving responses.
Area of Science:
- Physiology
- Cardiovascular Research
- Comparative Biology
Background:
- The diving response is a complex physiological adaptation observed in many air-breathing vertebrates.
- Understanding this response is crucial for studying mammalian adaptation to hypoxic environments.
Purpose of the Study:
- To investigate the cardiovascular and circulatory adjustments in rats during a simulated diving response.
- To evaluate the rat as a potential mammalian model for studying the diving reflex.
Main Methods:
- Head immersion in unanesthetized rats for 60 seconds.
- Monitoring heart rate, cardiac output, systemic arterial blood pressure, and total peripheral resistance.
- Measuring regional blood flow distribution to various organs and tissues.
Main Results:
- Significant reductions in heart rate (73%) and cardiac output (74%) were observed.
- Systemic arterial blood pressure increased by 22%, with a fourfold rise in total peripheral resistance.
- Selective blood flow redistribution occurred, with major reductions to the kidneys, intestines, spleen, tail, and skin, while coronary, cerebral, and bronchial circulations were maintained.
Conclusions:
- Rats display a diving response characterized by bradycardia, maintained stroke volume, hypertension, and significant peripheral vasoconstriction.
- The observed pattern of blood flow redistribution in rats closely resembles that of diving mammals.
- The rat serves as a viable cardiovascular model for further research into the mammalian diving response.