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Distension of central great vein decreases sympathetic outflow in humans
- Publication Year :
- 2013
- Publisher :
- American Physiological Society, 2013.
-
Abstract
- Classic canine studies suggest that central great vein distension evokes an autonomic reflex tachycardia (Bainbridge reflex). It is unclear whether central venous distension in humans is a necessary and sufficient stimulus to evoke a reflex increase in heart rate (HR), blood pressure (BP), and muscle sympathetic nerve activity (MSNA). Prior work from our laboratory suggests that limb venous distension evokes a reflex increase in BP and MSNA in humans. We hypothesized that in humans, compared with the limb venous distension, inferior vena cava (IVC) distension would evoke a less prominent increase in HR and MSNA. IVC distension (monitored with ultrasonography) was induced by two methods: 1) head-down tilt (HDT, N = 13); and 2) lower-body positive pressure (LBPP, N = 10). Two minutes of HDT induced IVC distension (Δ2.6 ± 0.2 mm, P < 0.001, ∼27% in cross-sectional area), slightly increased mean BP (Δ2.3 ± 0.7 mmHg, P = 0.005), decreased MSNA (Δ5.2 ± 0.8 bursts/min, P < 0.001, N = 10), and did not alter HR ( P = 0.37). LBPP induced similar IVC distension, increased BP (Δ2.0 ± 0.7 mmHg, P < 0.01), and did not alter HR ( P = 0.34). Thus central venous distension leads to a rapid increase in BP and a subsequent fall in MSNA. Central venous distension does not evoke either bradycardia or tachycardia in humans. The absence of a baroreflex-mediated bradycardia suggests that the Bainbridge reflex is engaged. Clearly, this reflex differs from the powerful sympathoexcitation peripheral venous distension reflex described in humans.
- Subjects :
- Tachycardia
Adult
Male
Sympathetic nervous system
medicine.medical_specialty
Sympathetic Nervous System
Time Factors
Cardiovascular Neurohormonal Regulation
Physiology
Blood Pressure
Vena Cava, Inferior
Baroreflex
Distension
Biochemistry
Cardiovascular System
Head-Down Tilt
Upper Extremity
Young Adult
Heart Rate
Physiology (medical)
Internal medicine
Reflex
Autonomic reflex
Genetics
medicine
Humans
Muscle, Skeletal
Molecular Biology
Ultrasonography
Lower Body Negative Pressure
Analysis of Variance
business.industry
Great saphenous vein
Hemodynamics
Anatomy
medicine.anatomical_structure
Cardiology
cardiovascular system
Female
medicine.symptom
Sympathetic outflow
Cardiology and Cardiovascular Medicine
business
Bainbridge reflex
Biotechnology
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....01da37db36dcf7123cd518b5aa4fc447