Abstract
PGE2 inhibits fetal breathing movements (FBM); the prostaglandin synthetase inhibitor, M, stimulates FBM. To determine if these effects are mediated through the peripheral chemoreceptors, we studied 13 chronically catheterized fetuses; 7 had bilateral sections of carotid sinus and vagus nerves; 6 had sham operations. FBM (by tracheal catheter) and electrocortical activity (ECoA) were recorded continuously. After a control (C) period (19.9±4.5h; mean±SD) we infused PGE2 (0.6±0.2 μg/kg/min) or M (0.4±0.2 mg/kg/h) for 20.0±2.1 h per infusion. Infusions were separated ≥ 48 h. The incidences and amplitudes of FBM were lower in the denervated group (Table).(values=mean±SD; °P<0.05 compared to C; ¶P<0.05 compared to Sham). However, the % change from C during infusions was similar in both groups as were the ECoA, arterial pH, PO2, PCO2 and pressures. We conclude that peripheral chemoreceptor denervation significantly affects FBM; however the effects of PGE2 and M on FBM are not mediated through the peripheral chemoreceptors. (USPHS HL-27356).
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