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Catecholamine-induced changes in vascular capacitance and sympathetic nerve activity in dogs
H Arimura1, Z J Bosnjak, S Hoka
1Department of Anesthesiology, Medical College of Wisconsin, Milwaukee 53226.
Canadian Journal of Physiology and Pharmacology
|July 1, 1992
Summary
This study investigated how dopamine, epinephrine, and dobutamine affect systemic blood volume (SBV) and sympathetic nerve activity in dogs. Dopamine and epinephrine significantly reduced SBV by causing splanchnic venoconstriction, an effect modulated by sympathetic discharge.
Area of Science:
- Cardiovascular Physiology
- Pharmacology
Background:
- Catecholamines like dopamine, epinephrine, and dobutamine are critical in regulating systemic circulation.
- Understanding their precise effects on systemic vascular capacitance and sympathetic nervous system activity is essential for clinical applications.
Purpose of the Study:
- To investigate the impact of dopamine, epinephrine, and dobutamine on systemic blood volume (SBV) and sympathetic efferent nerve activity (SENA).
- To elucidate the role of sympathetic discharge in mediating the vascular responses to these catecholamines.
Main Methods:
- The study utilized cardiopulmonary bypass in pentobarbital-anesthetized dogs.
- Systemic blood volume changes were calculated from venous outflow measurements (splanchnic, renal, other).
- Sympathetic efferent nerve activity (SENA) was recorded, and experiments were conducted under control, baroreceptor deafferentation, and hexamethonium conditions with varying catecholamine doses.
Main Results:
- Dopamine and epinephrine significantly reduced SBV after hexamethonium, primarily through splanchnic venoconstriction.
- High doses of dopamine and epinephrine suppressed SENA, an effect modified by baroreceptor deafferentation.
- Dobutamine reduced SBV but did not affect SENA.
Conclusions:
- Dopamine and epinephrine decrease systemic blood volume mainly via splanchnic venoconstriction.
- The vascular effects of dopamine and epinephrine are significantly influenced by basal sympathetic tone and alterations in sympathetic efferent nerve activity.
- Dobutamine's effect on SBV is independent of sympathetic efferent nerve activity.