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Plasma catecholamine response in trained rats following hemorrhage
1Départment des Sciences de l'activité physique, Université du Québec à Trois-Rivières, PQ.
Summary
Physical training reduces epinephrine release during hemorrhage in rats. Trained rats showed lower plasma epinephrine levels post-hemorrhage, suggesting altered hormonal responses to blood loss.
Area of Science:
- Physiology
- Exercise Science
- Endocrinology
Background:
- Hemorrhage triggers a significant release of catecholamines, including epinephrine and norepinephrine, as part of the body's stress response.
- Physical training is known to alter cardiovascular and endocrine functions, but its specific impact on catecholamine release during acute stress like hemorrhage is not fully understood.
Purpose of the Study:
- To investigate the influence of a 14-week physical training program on catecholamine (epinephrine and norepinephrine) release in rats subjected to hemorrhage.
- To compare the cardiovascular and hormonal responses to hemorrhage between trained and untrained rats.
Main Methods:
- A 14-week swimming exercise protocol was implemented for trained rats, gradually increasing duration.
- Rats were divided into four groups: trained hemorrhage, untrained hemorrhage, trained control, and untrained control.
- Blood pressure, heart rate, hematocrit, and plasma catecholamine levels (epinephrine and norepinephrine) were measured before and after induced hemorrhage.
Main Results:
- Trained rats exhibited a significantly lower resting heart rate compared to untrained rats.
- Both trained and untrained groups showed similar blood pressure, hematocrit, and norepinephrine responses to hemorrhage.
- Plasma epinephrine concentration was significantly lower in trained rats at 15 and 25 minutes post-hemorrhage.
Conclusions:
- Physical training attenuates the epinephrine response to hemorrhage in rats.
- The reduced epinephrine secretion in trained rats may be linked to alterations in arterial baroreflex sensitivity and their associated hormonal effector pathways.