What question did this study set out to answer?

To determine whether nervous feedback mechanisms control exercise ventilation and circulation independently of humoral factors during partial neuromuscular blockade.

March 1, 1965Acta Physiologica Scandinavica

On the Nervous Factors Controlling Respiration and Circulation during Exercise Experiments with curarization

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Why the study?

Does (+) tubocurarine affect respiration and circulation during steady state exercise?

Population

Subjects performing steady state work on a bicycle ergometer

Design

Other

Follow-up

20 to 30 min

Authors

EAErling AsmussenUniversity of Copenhagen SJSøren JohansenUniversity of Copenhagen MJMogens JørgensenNy Carlsberg Glyptotek

Discussion

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Implication

May inform neural control of exercise ventilation; hypothesis-generating and should not change curare use or guidelines.

Key Points

To determine whether nervous feedback mechanisms control exercise ventilation and circulation independently of humoral factors during partial neuromuscular blockade.
Administered repeated intravenous injections of (+) tubocurarine during steady-state bicycle ergometer exercise maintained for 20 to 30 minutes.
Measured handgrip strength, heart rate, blood pressure, cardiac output, oxygen uptake, and ventilation throughout constant-intensity work.
Maintained alveolar PCO2 at normal exercise levels by adding carbon dioxide to inspired air to keep humoral respiratory stimuli constant.
Pulmonary ventilation increased by up to approximately 50%, both in absolute terms and relative to oxygen uptake, despite maintaining constant external work intensity.
Cardiac output remained uninfluenced by tubocurarine administration, while pulse rate and blood pressure showed slight and irregular increases.
Because alveolar PCO2 and humoral factors remained normal, the ventilatory surge indicates a nervous mechanism driven by muscle spindle afferents feeding into the reticular formation.

Structured PICO

Does (+) tubocurarine affect respiration and circulation during steady state exercise?

Population

Subjects performing steady state work on a bicycle ergometer

Intervention

Repeated i.v. injections of (+) tubocurarine

Outcome

Changes in ventilation, pulse rate, blood pressure, and cardiac outputsurrogate

The study suggests that nervous factors, potentially afferent impulses from muscle spindles, play a key role in respiratory regulation during exercise.

Cite This Study

Asmussen et al. (1965) studied this question.

synapsesocial.com/papers/6a70318735aa2c282ce17e09 https://doi.org/10.1111/j.1748-1716.1965.tb04073.x

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On the Nervous Factors Controlling Respiration and Circulation during Exercise Experiments with curarization

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

On the Nervous Factors Controlling Respiration and Circulation during Exercise Experiments with curarization

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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