Journal of Applied Physiology, Vol 47, Issue 5 927-930, Copyright © 1979 by American Physiological Society
Maturation of hypoxic ventilatory response of the newborn lamb
D. A. Belenky, T. A. Standaert and D. E. Woodrum
The ventilatory response to acute hypoxia was studied in unanesthetized
newborn lambs before and after carotid body denervation. Animals studied
immediately following operative delivery were compared with a second group
who were studied in the 2nd wk of postnatal life. Response time was defined
as the interval between the decrease in oxygen saturation in the aortic
arch and an increase in tidal volume or ventilatory rate. Animals in the
older group demonstrated a significantly shorter response time than those
studied immediately following delivery (1.8 s vs. 5.7 s). A ventilatory
response was also elicited in carotid body-denervated animals in both study
groups. Mean response time following denervation was 29.5 s for the younger
and 12.5 s for the older animals. The data suggest that the development of
a rapid, carotid body-mediated hypoxic ventilatory response occurs
gradually during the first days of postnatal life, and that the central
hypoxic response of the fetus (J. Appl. Physiol.: Respirat. Environ.
Exercise Physiol. 42:630-635, 1977) persists into postnatal life.
