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Intrathecal serotonin attenuates the pressor response to static contraction
1Department of Internal Medicine, University of California, Davis 95616.
Brain Research
|May 31, 1991
Summary
Intrathecal serotonin injection in cats reduces blood pressure increases during muscle contraction. This effect is mediated by 5-HT1 receptors in the spinal cord, highlighting serotonin's role in cardiovascular regulation.
Area of Science:
- Neuroscience
- Cardiovascular Physiology
- Pharmacology
Background:
- The pressor response to static muscle contraction is a reflex that increases blood pressure.
- The role of spinal serotonin in modulating this reflex is not fully understood.
Purpose of the Study:
- To investigate the effect of intrathecal serotonin on the pressor response to static muscle contraction in cats.
- To determine the specific serotonin receptor subtypes involved in this modulation.
Main Methods:
- Intrathecal injections of serotonin, mianserin hydrochloride (serotonergic antagonist), carboxamidotryptamine maleate (5-HT1 agonist), and DOI-hydrochloride (5-HT2 agonist) were administered to chloralose-anesthetized cats.
- The pressor response to static contraction of the triceps surae muscles was measured.
- Ventilatory responses were also monitored.
Main Results:
- Serotonin significantly attenuated the reflex increases in mean arterial pressure during muscle contraction.
- This attenuation was blocked by mianserin hydrochloride, indicating a serotonergic mechanism.
- Carboxamidotryptamine maleate (5-HT1 agonist) also attenuated the pressor response, while DOI-hydrochloride (5-HT2 agonist) did not.
- Ventilatory responses were not affected by serotonin.
Conclusions:
- Stimulation of 5-HT1 receptors in the lumbosacral spinal cord attenuates the reflex pressor response to static muscular contraction.
- Spinal serotonin plays a role in regulating cardiovascular responses to exercise.