AJP - Regulatory, Integrative and Comparative Physiology, Vol 258, Issue 5 1213-R1216, Copyright © 1990 by American Physiological Society
No effect of prostaglandin synthesis inhibition on muscle reflexes in fetal lambs
D. Walker
Department of Physiology, Monash University, Clayton, Melbourne, Victoria.
The effects of inhibiting prostaglandin (PG) synthesis on fetal breathing
movements and on the amplitude of reflex contraction of the digastric
muscle (five trials) or hindlimb semitendinosus muscle (seven trials) has
been studied in six fetal lambs at 123-139 days gestation. Infusion of
either indomethacin (100 mg) or acetaminophen (300 mg) in 30 ml saline over
30 min resulted in an increase in the amplitude and incidence of breathing
movements for 3-18 h in the different trials, but there was no change in
the mean amplitude of either reflex or in the normal variation of reflex
amplitude with changes in electrocortical activity. It is concluded that
PGs modulate fetal breathing movements by an action on the brain stem
chemoreceptors but do not alter the excitability of neural pathways
subserving some cranial and spinal reflexes.
