Project Details

Description

This proposal will test the hypothesis of bidirectional positive feedback
at the central chemoreceptors for ventilatory control. We propose that
activation of a group of neurons near the central chemoreceptors such as
the ventral respiratory group can increase local metabolism, cause the
elaboration of acid metabolites and thereby stimulate the central
chemosensitive cells. Such a mechanism would constitute a positive
feedback loop in the respiratory control system and could explain phenomena
such as isocapnic hyperpnea associated with hypermetabolism. In addition,
a positve feedback loop of this nature could be bidirectional since an
increase in local blood flow in excess of metabolism would reduce the
extracellular [H+] resulting in a diminuation of respiratory drive. This
proposal concerns itself with the investigation of this hypothesis of
bidirectional positive feedback in respiratory control using
autoradiographic and microelectrode techniques. In cats we propose to
determine the relationships of ventral medullary blood flow
(iodo- 14 C-antipyrine method) and metabolism (2 deoxy- 14 C-glucose
method), as well as the pH in the ventral medulla (microelectrodes) during
two situations of increased respiratory drive without associated blood gas
changes: (a) carotid sinus nerve stimulation in a paralyzed artificially
ventilated animal; and (b) simulated exercise. Secondly, we will measure
ventral medullary blood flow during two situations of decreased respiratory
drive which we postulate to be the result of a descreased extracellular
[H+] consequential to excess perfusion: (a) hypoxia in peripherally
chemodenervated cats; and (b) REM sleep. Should the hypothesis prove
correct, it will enhance understanding of heretofore obscure phenomena such
as isocapnic hyperpnea, depression of ventilation due to CNS hypoxia and
breathing irregularities during REM sleep.
StatusFinished
Effective start/end date1/1/836/30/86

Funding

  • National Institutes of Health

ASJC

  • Medicine(all)

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