Ganglioglomerular nerves respond to moderate hypoxia independent of peripheral chemoreceptors in the cat.
The responses of the ganglioglomerular nerve (GGN) to transient changes and steady-state levels of paO2 at a constant paCO2 were studied in 12 anesthetized and spontaneously breathing cats before and after bilateral section of aortic (AN) and carotid sinus nerves (CSN). In two of these cats carotid chemoreceptor activity was monitored simultaneously. Onset of moderate hypoxia, down to paO2 of about 50 Torr, stimulated GGN activity and withdrawal of the hypoxic stimulus promptly eliminated the responses both before and after CSN section. CSN section, however, significantly raised the baseline activity and slightly delayed the GGN response to the onset of hypoxia. These responses to hypoxia are qualitatively similar to the characteristic responses of peripheral chemoreceptors. Thus, the basic oxygen chemosensing mechanism appeared to be present in the sympathetic nervous system, and is expressed in the postganglionic GGN activity. This property allows the sympathetic nervous system to perform physiologically important functions independent of the peripheral chemoreceptors.
D000818:Animals; D002346:Carotid Sinus / Q000294:innervation; D002415:Cats; D002628:Chemoreceptor Cells / Q000503:physiopathology*; D005260:Female; D000860:Hypoxia / Q000503:physiopathology*; D009412:Nerve Fibers / Q000503:physiopathology; D009420:Nervous System / Q000503:physiopathology*