Breathing response to lung congestion with and without left heart distension

tim with and without left heart distension, J. Appl. Physiol. 65(l): 131-136, 1988.-This study compared the effect of lung congestion with and without left heart (LH) distension on breathing frequency (fr) and discriminated among responses mediated by myelinated and nonmyelinated vagal afferents. Cardiopulmonary bypass perfusion of anesthetized dogs was used to isolate reflexes. The following three groups were pre-pared: 1) lung vessels pressurized by pumping into the main pulmonary artery (MPA); 2) lungs and fibrillating LH pressur-ized by pumping into MPA while draining from LH; 3) lungs congested by occluding several pulmonary veins while holding cardiac output constant. Congestion of lungs alone in groups 1 and 3 depressed fr. Congestion of lungs and distension of LH (group 2) caused transient depression of fr but a steady-state excitation. Cooling cervical vagi to 8°C prevented depressio