AJP - Heart and Circulatory Physiology, Vol 248, Issue 6 867-H875, Copyright © 1985 by American Physiological Society
Cephalic carotid pressure as a measure of transmission through cervical ganglion
R. S. Tuttle
Cephalic or cranial pressure, i.e., pressure recorded craniad from the
external carotid artery, was recorded in the cat during stimulation of the
pre- and postganglionic trunks of the superior cervical ganglion (SCG) as
was tension developed by the nictitating membrane under these situations.
The influence of distension of the carotid sinus and of metoprolol on
hemodynamic and tension responses was compared with control responses.
Distension of the sinus with an indwelling balloon produced an increase of
cephalic pressure evoked by stimulation of the SCG. Tension developed by
the nictitating membrane was unaffected. Metoprolol reduced the increase in
pressure resulting from stimulation of the preganglionic trunk of the SCG
at 1.0 Hz but enhanced the pressure increase in the cranial circulation
evoked by postganglionic stimulation of the SCG at 5.0 Hz. Action
potentials, recorded postganglionically from the SCG, could be roughly
grouped by height and latency into three populations. The height of the M3
population increased with distension of the carotid sinus. This study
provides evidence that cephalic pressure can be used as a measure of the
influence of various factors on the transmission of impulses through the
SCG. This parameter appears to be a more sensitive measure of transmission
than that of tension developed by the nictitating membrane. Distension of
the carotid sinus is one factor that facilitates ganglionic transmission,
whereas the beta-adrenoceptor antagonist metoprolol depresses it.
