ORIGINS OF THE EXERCISE REFLEX

  • Stebbins, Charles L (PI)

Project: Research project

Project Details

Description

The objective of this proposed research is to address specific deficiencies
in our understanding of the chemical factors within contracting muscle that
contribute to the reflex cardiovascular response to exercise. A better
understanding of these factors may allow physicians to modify these
responses where they may be harmful, for instance in patients with ischemic
heart disease. The specific aims and methodologies are: 1) determination
of the reflex potential of chemical stimuli released during muscular
contraction. This will be accomplished by stimulating the cat's skeletal
muscle with intra-arterial injections of each chemical to evoke a
cardiovascular response. The reflex nature of the response will be
confirmed by denervation of the gracilis. 2) Evaluation of the
contribution of those chemical stimuli with reflex potential to the reflex
cardiovascular response evoked by static muscular contraction. To evaluate
the potential contribution of each chemical, the cardiovascular response to
ventral root stimulated static contraction will be attenuated by inhibiting
the production or action of the substance pharmacologically or by enhancing
its degradation by infusing the appropriate enzyme responsible for
catabolism. Alternatively, the degradation of a given chemical will be
inhibited pharmacologically to demonstrate an augmented contraction-induced
cardiovascular response. 3) Evaluation of the relationship between changes
in interstitial PO2, PCO2 and pH to the onset and magnitude of the
cardiovascular response to electrically stimulated contraction. To study
this effect, skeletal muscle interstitial PO2, PCO2 and pH will be measured
with mini-electrodes during contraction and contraction accompanied with
ischemia. The time course and magnitude of changes in these variables will
be compared to the onset and magnitude of the cardiovascular responses to
contraction and contraction with ischemia. The cardiovascular response to
pharmacological stimulation and hindlimb contraction will be evaluated by
assessing changes in arterial blood pressure, heart rate and
contractility. In some animals changes in preload, aortic flow and
systemic vascular resistance also will be assessed.
StatusFinished
Effective start/end date7/10/856/30/89

Funding

  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health

ASJC

  • Medicine(all)

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