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February 1, 1990Acta Physiologica Scandinavica

Cardiovascular responses to carotid sinus baroreceptor stimulation during moderate to severe exercise in man

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Why the study?

Does carotid sinus baroreceptor stimulation alter cardiovascular responses and muscle blood flow during moderate to severe exercise in humans?

Population

8 subjects exercising on a cycle ergometer at three levels requiring 40-88% of VO2 max

Comparison

Pulsatile negative pressure applied over the… vs Before each neck suction (baseline)

Design

Other

Authors

SSS. StrangeDanish Medical AssociationLRL. B. RowellCross-Cutting CardiologyNCNiels Juel ChristensenUniversity of Wisconsin–Madison

Discussion

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Overview

Baroreflex stimulation fails to increase active muscle conductance at severe exercise; leaves open non-baroreflex sources of vasoconstrictor tone.

Key Points

  • To evaluate the role of arterial baroreflexes in regulating sympathetic vasoconstriction within active skeletal muscle during moderate to severe cycle exercise.
  • Studied 8 subjects performing cycle ergometer exercise across three workloads averaging 94 W, 194 W, and 261 W (40% to 88% of VO2 max).
  • Applied ECG-gated pulsatile negative pressure (-50 mmHg for 250–400 ms) over the carotid sinuses for 30-second intervals during each exercise stage.
  • Measured femoral venous blood flow before and during neck suction using constant-infusion thermal dilution alongside heart rate and blood pressure recording.
  • At 94 W, neck suction decreased blood pressure by 15 mmHg and heart rate by 7 beats/min, while increasing leg vascular conductance by 11.4% with unchanged femoral venous blood flow.
  • At 194 W, suction reduced blood pressure by 9 mmHg, heart rate by 4 beats/min, and femoral venous blood flow by 5.1% (240 ml/min), while leg vascular conductance increased by 5.2%.
  • At 261 W, leg vascular conductance remained unchanged during suction, but blood pressure fell by 9 mmHg and femoral venous blood flow dropped by 7.4% (650 ml/min).

Structured PICO

Does carotid sinus baroreceptor stimulation alter cardiovascular responses and muscle blood flow during moderate to severe exercise in humans?

P
Population
8 subjects exercising on a cycle ergometer at three levels (averages 94, 194, 261 W) requiring 40-88% of VO2 max
I
Intervention
Pulsatile negative pressure (-50 mmHg) applied over the carotid sinuses for 30 s (suction applied at each ECG R-wave for 250-400 ms) during exercise
C
Comparator
Before each neck suction (baseline)
O
Outcome
Femoral venous blood flow (FVBF), blood pressure (BP), heart rate (HR), and leg vascular conductance (LVC)surrogate

Baroreceptor stimulation can withdraw vasoconstrictor tone during moderate exercise, but high levels of vasoconstrictor outflow during severe exercise may not originate from baroreflexes.

Cite This Study

Strange et al. (1990) studied this question.

synapsesocial.com/papers/6a82791c32876fda9aac8fb0https://doi.org/10.1111/j.1748-1716.1990.tb08826.x
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Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

  1. 1Maintained ability of carotid baroreflex to regulate arterial pressure during exercise1981 · 144 citations
  2. 2Baroreflex responsiveness is maintained during isometric exercise in humans1986 · 55 citations
  3. 3Effects of graded pulsatile pressure on the reflex vasomotor responses elicited by changes of mean pressure in the perfused carotid sinus‐aortic arch regions of the dog1971 · 71 citations
  4. 4Comparison of aortic and carotid baroreflexes in the dog1971 · 120 citations
  5. 5Blood flow and oxygen consumption in skeletal muscle during sympathetic stimulation1983 · 45 citations