AJP - Heart and Circulatory Physiology, Vol 242, Issue 5 916-H920, Copyright © 1982 by American Physiological Society
Denervation of arterial chemoreceptors and baroreceptors in fetal lambs in utero
J. Itskovitz and A. M. Rudolph
Arterial baroreceptors and chemoreceptors were denervated in eight fetal
lambs in utero. Carotid sinus and carotid body denervation was accomplished
by stripping the carotid artery rostral and caudal to the origin of the
occipital and lingual arteries. Aortic bodies were denervated by section of
the superior laryngeal nerve and aortic nerve in the neck. The anatomy
relevant to the technique is presented. The effectiveness of the
denervation was tested by injection of 20 micrograms phenylephrine. The
slowing of the fetal heart rate normally present in the intact lambs was
abolished in the denervated fetuses. Denervation of the carotid and aortic
chemoreceptors abolished the reflex bradycardia following injection of 200
micrograms cyanide or following acute hypoxemia produced by uterine blood
flow reduction for 20 s. These results indicate that the baroreflex and
chemoreflex can be elicited in utero and eliminated by the method we
described. The preparation we present allows the study of the role of the
arterial chemoreceptors and baroreceptors in normal fetal cardiovascular
regulation and in fetal responses to stress.
