Premium
μ‐Opioid Receptor‐Sensitive Muscle Afferents Contribute to the Circulatory Response to Exercise in Humans
Author(s) -
Amann Markus,
Runnels Sean,
Morgan David E,
Trinity Joel,
Fjeldstad Anette,
Wray David W,
Richardson Russell S
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1054.7
Subject(s) - circulatory system , medicine , opioid , opioid receptor , neuroscience , receptor , biology
We investigated the role of somatosensory feedback on hemodynamic and ventilatory responses to exercise. Nine males performed knee‐extensor exercise (15/30/45 W, 3‐min each) with and without lumbar intrathecal fentanyl (L3–L4) impairing the central projection of spinal μ‐opioid receptor‐sensitive muscle afferents. Femoral venous and arterial catheterization was combined with Doppler femoral blood flow measures (FBF). Pulmonary/hemodynamic variables were recorded continuously, FBF measures and blood was simultaneously taken during the final min of each workload. To evaluate whether a cephalad migration of fentanyl affected cardioventilatory control centers in the brainstem, we compared resting hypercapnic ventilatory responses (HCVR). Similar HCVR excluded direct medullary effects of fentanyl. Resting measures were similar between conditions. Cardiac output was 19–22% lower during Fentanyl exercise, secondary to significant reductions in heart rate and stroke volume. Throughout Fentanyl exercise, FBF, arterial pressure and vascular conductance were 14–16%, 6–7%, and 8–10% lower (p < 0.05). Venous pressure was similar in both conditions. Ventilation during Fentanyl exercise was 4–7% lower leading to a 1–1.5 mmHg increase in arterial PCO 2 (p < 0.05). Our findings demonstrate the essential contribution of muscle afferents to hemodynamic and ventilatory responses to rhythmic human exercise.