Effect on breathing of ventral medullary surface cooling in
neonatal goats.
Lowry, T. F., H. V. Forster, L. G. Pan, P. J. Ohtake, I. Epshteyn, M.
J. Korducki, and R. A. Franciosi.
Departments of Physiology and Pathology, Medical College of
Wisconsin, Zablocki Veterans Administration Medical Center, and
Program in Physical Therapy, Marquette University, Milwaukee, WI
53226
APStracts 3:0096A, 1996.
The present study was designed to determine whether neurons near the
ventral medullary surface (VMS) that are important to control of
breathing in adult mammals are also important to control of breathing
in neonates. In 7 day old goats (n=22), the VMS was surgically
exposed under halothane anesthesia. Stainless steel thermodes (2 mm x
2 mm) were used to cool (20 degrees C) and thereby create neuronal
dysfunction of discrete VMS sites. Bilateral cooling under anesthesia
0-2 or 2-4 mm lateral to the midline between the exit of cranial
nerves VI and XII resulted in a reduction (P<.05) of breathing
and most often in apnea. Cooling caudal or rostral to this area did
not have a consistent effect on breathing. In 7 day old goats (n=8),
3 mm x 3 mm thermodes were chronically implanted bilaterally on the
VMS surface between the exit of cranial nerves VI and XII. The goats
were recovered and studied over several days thereafter. VMS cooling
while awake caused breathing to decrease (P<.05) but apnea was
never observed. The decrease was less (P<.05) than while
anesthetized. After 10 seconds of cooling, the hypopnea while awake
was uniform during eupnea, hypercapnia, hyperoxia and hypoxia, but
after 10 seconds of cooling, the decrease was relatively greater
(P<.05) during hyperoxia and hypercapnia. These effects of VMS
cooling are qualitatively the same as in adult goats; thus, the data
are consistent with mature VMS contribution to the control of
breathing in neonatal goats.
Received 17 October 1995; accepted in final form 9 January 1996.
APS Manuscript Number A1119-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 14 February 96