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Reflex modulation of lymphatic pumping in sheep.
1Department of Physiology and Biophysics, University Medical Center, Jackson, Mississippi.
Circulation Research
|June 1, 1989
Summary
Sympathetic nervous system activation enhances lymphatic pumping in sheep. This effect, mediated by catecholamines, is crucial for lymphatic fluid propulsion and can be modulated by alpha-adrenergic blockade.
Area of Science:
- Physiology
- Cardiovascular System
- Lymphatic System
Background:
- The lymphatic system is vital for fluid balance and immune function.
- Lymphatic pumping is essential for lymph transport.
- Factors influencing lymphatic pumping require further investigation.
Purpose of the Study:
- To investigate the effect of sympathetic nervous system activation on lymphatic pumping.
- To explore the role of catecholamines and alpha-adrenergic receptors in this process.
Main Methods:
- Utilized an isolated mesenteric lymph duct preparation in halothane-anesthetized sheep.
- Evoked a cerebral ischemic response to stimulate sympathetic activity.
- Administered phentolamine (an alpha-adrenergic antagonist) to assess its impact.
Main Results:
- Cerebral ischemia significantly increased lymphatic fluid propulsion.
- Phentolamine administration initially increased, then decreased lymphatic pumping.
- Sympathetic stimulation after phentolamine administration failed to increase lymphatic pumping.
- Adrenalectomy reduced resting lymph propulsion and attenuated the response to ischemia.
Conclusions:
- Reflex sympathetic activation increases mesenteric lymphatic pumping.
- Circulating catecholamines likely augment this response.
- Alpha-adrenergic receptors play a role in modulating lymphatic pumping during sympathetic activation.