FBM in chronic ovine fetal preparations are not affected by vagus or carotid sinus nerve sections. However, the aortic bodies may acquire respiratory chemoreceptivity after carotid body denervation. To better define the role of these chemoreceptors on the control of FBM, we chronically studied 14 fetuses; 7 had bilateral section of carotid sinus and vagus nerves and 7 had sham operations. FBM (by tracheal catheter) and electrocortical activity (ECoA) were recorded continuously after surgery. The incidence of FBM and amplitudes of tracheal pressure during 2 periods, 1-5 and 6-13 postoperative (PO) days were:
[Values=X̄(SD); all comparisons of denerv to sham, p<0.05 except day 5.] ECoA, arterial pH, PO2, PCO2 and blood pressures were similar in both groups. Throughout this study, the daily mean incidence of FBM and tracheal pressures during FBM in the denervated group were lower than in the sham group. We conclude that total peripheral chemoreceptor denervation significantly affects the incidence and amplitudes of FBM in sheep. (USPHS HL-27356).