Diving and exercise: The interaction of trigeminal receptors and muscle metaboreceptors on muscle sympathetic nerve activity in humans

作者：Fisher James P; Fernandes Igor A; Barbosa Thales C; Prodel Eliza; Coote John H; Nobrega Antonio Claudio L; Vianna Lauro C

来源：American Journal of Physiology - Heart and Circulatory Physiology, 2015, 308(5): H367-H375.

DOI：10.1152/ajpheart.00728.2014

• autonomic
• diving response
• cardiovascular

Swimming involves muscular activity and submersion, creating a conflict of autonomic reflexes elicited by the trigeminal receptors and skeletal muscle afferents. We sought to determine the autonomic cardiovascular responses to separate and concurrent stimulation of the trigeminal cutaneous receptors and metabolically sensitive skeletal muscle afferents (muscle metaboreflex). In eight healthy men (30 +/- 2 yr) muscle sympathetic nerve activity (MSNA; microneurography), mean arterial pressure (MAP; Finometer), femoral artery blood flow (duplex Doppler ultrasonography), and femoral vascular conductance (femoral artery blood flow/MAP) were assessed during the following three experimental conditions: 1) facial cooling (trigeminal nerve stimulation), 2) postexercise ischemia (PEI; muscle metaboreflex activation) following isometric handgrip, and 3) trigeminal nerve stimulation with concurrent PEI. Trigeminal nerve stimulation produced significant increases in MSNA total activity (Delta 347 +/- 167%) and MAP (Delta 21 +/- 5%) and a reduction in femoral artery vascular conductance (Delta - 17 +/- 9%). PEI also evoked significant increases in MSNA total activity (Delta 234 +/- 83%) and MAP (Delta 36 +/- 4%) and a slight nonsignificant reduction in femoral artery vascular conductance (Delta - 9 +/- 12%). Trigeminal nerve stimulation with concurrent PEI evoked changes in MSNA total activity (Delta 341 +/- 96%), MAP (Delta 39 +/- 4%), and femoral artery vascular conductance (Delta - 20 +/- 9%) that were similar to those evoked by either separate trigeminal nerve stimulation or separate PEI. Thus, excitatory inputs from the trigeminal nerve and metabolically sensitive skeletal muscle afferents do not summate algebraically in eliciting a MSNA and cardiovascular response but rather exhibit synaptic occlusion, suggesting a high degree of convergent inputs on output neurons.

• 出版日期2015-3-1