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Alteration of chemoreflex phrenic responses by oligomycin in the rabbit
Abstract:
The effects of carotid chemoreceptor stimulation by intracarotid injections of sodium cyanide (NaCN, 30 micrograms), antimycin A (AMC, 10 micrograms) and dopamine (DA, 10 micrograms) on phrenic nerve activity were studied before and after oligomycin (200 micrograms) in the rabbit. The excitatory responses to NaCN and AMC were abolished after intracarotid administration of oligomycin, whereas the DA-induced phrenic depression was only slightly diminished. In addition, the effects of hypoxia on phrenic nerve activity were also studied before and after oligomycin (200 micrograms) in some animals with denervated one carotid sinus nerve. The hypoxia-induced phrenic excitation was greatly reduced after intracarotid administration of oligomycin. These results indicate that the chemoreflex phrenic responses induced by NaCN, AMC and hypoxia are probably related to the phosphate potential in the carotid body.
Insights
Carotid chemoreceptor stimulation by sodium cyanide (NaCN) and antimycin A (AMC) affects phrenic nerve activity. Oligomycin abolished these excitatory responses, suggesting a role for phosphate potential in carotid body chemoreflexes.
Area of Science:
- Respiratory Physiology
- Neuroscience
- Cellular Metabolism
Background:
- Carotid chemoreceptors play a vital role in regulating breathing.
- The precise mechanisms underlying carotid chemoreceptor stimulation, particularly the role of cellular energy status, require further elucidation.
Purpose of the Study:
- To investigate the impact of oligomycin, an inhibitor of oxidative phosphorylation, on carotid chemoreceptor-mediated phrenic nerve activity.
- To determine the relationship between carotid body phosphate potential and chemoreflex responses to various stimuli.
Main Methods:
- Intracarotid injections of sodium cyanide (NaCN), antimycin A (AMC), and dopamine (DA) in rabbits.
- Measurement of phrenic nerve activity before and after oligomycin administration.
- Assessment of hypoxic responses in rabbits with denervated carotid sinus nerves.
Main Results:
- Oligomycin abolished the excitatory phrenic responses to NaCN and AMC.
- Dopamine-induced phrenic depression was only slightly affected by oligomycin.
- Hypoxia-induced phrenic excitation was significantly reduced after oligomycin treatment.
Conclusions:
- Carotid chemoreflex responses to NaCN, AMC, and hypoxia are likely mediated by changes in the carotid body's phosphate potential.
- Phosphate potential is a critical factor in the excitatory signaling of carotid chemoreceptors.