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Baroreceptor control of the cutaneous active vasodilator system
C G Crandall1, J M Johnson, W A Kosiba
1Department of Physiology, University of Texas Health Science Center at San Antonio 78284, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 1, 1996
Summary
Neither cardiopulmonary nor carotid baroreflex unloading solely explains reduced skin vasodilation during simulated orthostasis. This study investigated baroreceptor roles in regulating cutaneous active vasodilation under stress.
Area of Science:
- Physiology
- Cardiovascular Regulation
- Thermoregulation
Background:
- Simulated orthostasis (standing) triggers reflexes that reduce skin blood flow.
- The specific baroreflexes (cardiopulmonary vs. carotid) responsible for this cutaneous vasodilation reduction remain unclear.
Purpose of the Study:
- To determine if cardiopulmonary or carotid baroreflex unloading alone causes reduced cutaneous active vasodilation during simulated orthostasis.
- To differentiate the roles of cardiopulmonary and carotid baroreceptors in the sympathetic nervous system's control of skin blood flow.
Main Methods:
- Lower body negative pressure (LBNP) was used to unload cardiopulmonary baroreceptors.
- Carotid pressure (CP) was applied to unload carotid baroreceptors.
- Skin blood flow was measured at adrenergic-blocked and unblocked sites during normothermia and hyperthermia.
- Forearm vascular conductance (FVC) and cutaneous vascular conductance (CVC) were assessed.
Main Results:
- Low levels of LBNP (-5 to -10 mmHg) did not alter heart rate (HR) or CVC but reduced FVC.
- Higher LBNP (-30 mmHg) reduced CVC, FVC, and increased HR.
- Carotid pressure (CP) did not affect FVC or CVC but increased HR and mean arterial pressure.
- Neither LBNP nor CP alone fully replicated the cutaneous vasodilation changes seen in orthostasis.
Conclusions:
- Selective unloading of cardiopulmonary baroreceptors at low levels does not inhibit cutaneous active vasodilation.
- Selective carotid baroreceptor unloading does not inhibit cutaneous active vasodilation.
- The observed inhibition of cutaneous active vasodilation during simulated orthostasis likely involves integrated responses from multiple baroreceptor systems and potentially other neural pathways.