The pulmonary vascular response to combined activation of the muscle metaboreflex and mechanoreflex

Muscle metabo- and mechanoreflexes are known to influence systemic cardiovascular responses to exercise. Whether interplay between these reflexes is operant in the control of the pulmonary vascular response to exercise is unknown. The aim of this study was to assess the pulmonary vascular response to the combined activation of the two muscle reflexes. Nine healthy subjects performed a bout of isometric calf plantarflexion exercise during local circulatory occlusion, which was continued for 9 minutes post-exercise (PECO). At 5 minutes into PECO the calf muscle was passively stretched for 180 s. A control (no exercise) protocol was also undertaken. Heart rate and blood pressure measurements and echocardiographically determined estimates of systolic pulmonary artery pressure (SPAP) and cardiac output Q , were obtained at intervals throughout the two protocols. Elevations in SPAP (22.51±2.61%), Q (26.92±2.99%) and mean arterial pressure MAP (15.38±2.29%) were noted during isometric exercise as compared to baseline (All P