• Hempleman, Steven C (PI)

Project: Research project

Grant Details


The discharge patterns of carotid body chemoreceptors will be studied. An
avian animal model was chosen because their carotid bodies are nearly
identical in structure and function to those of mammals, and because the
avian lung offers the powerful experimental advantage of unidirectional
ventilation (UDV) for controlling arterial blood gases. Experiments are
proposed that combine UDV, on line blood gas measurement, single unit
neural recording techniques, measurements of reflex ventilatory responses,
and computerized on-line data acquisition to test the physiological
responses of carotid bodies in ways difficult or impossible with a
mammalian model. Carotid body chemoreceptors are multimodal, responding to arterial PO2,
PCO2, and other stimuli. This project will determine the response of
single receptors to arterial PO2, PCO2, pH, and blood pressure. This
project will also analyze the temporal occurrence of action potential from
chemoreceptors exposed to different static level of arterial PO2 and PCO2
(controlled with UDV) to test the hypothesis that the two stimuli cause
different receptor discharge patterns. Pattern differences could be a
neural encoding mechanism for carrying differential stimulus information
centrally, and might be due to difference in transduction mechanisms for
oxygen and carbon dioxide. Dynamic oscillations of arterial PCO2 associated with tidal breathing are
thought to provide a phasic, centrally gated ventilatory stimulus, and
perhaps a feed-forward control signal related to metabolic rate. This
project will use precise UDV induced arterial PCO2 oscillations to test the
rate sensitivity of carotid boy chemoreceptors (which would amplify their
oscillatory signal) and their frequency response. The reflex importance of
arterial PCO2 oscillations mediated by carotid body chemoreceptors will
also be quantitated. Many aspects of the normal dynamic and static carotid body chemoreceptor
sensitivity remain uncertain. It is important to study these normal
physiological responses to define the role of the carotid body in the
control of pulmonary ventilation in health and disease.
Effective start/end date4/1/893/31/90


  • National Institutes of Health


  • Medicine(all)


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