In vivo and in vitro responses of neurons in the ventrolateral medulla to hypoxia.

摘要: Neurons in the ventrolateral medulla (VLM) are known to be involved several cardiorespiratory reflexes and provide tonic drive sympathetic preganglionic neurons. Recent studies have suggested that VLM neurons modulate respiratory responses hypoxia hypercapnia. The purpose of present study was determine with electrophysiological techniques if discharge these is altered by and/or hypercapnia both vivo vitro. Extracellular single-unit activity (n = 39) recorded during inhalation a hypoxic gas (10% O2) hypercapnic (5% CO2) anesthetized, spontaneously breathing rats 16). Hypoxia elicited an increase frequency 64% studied; stimulated 42% Fifty-two percent were Signal averaging revealed 76% hypoxia-stimulated had resting related cardiac cycle. Similar percentages (35/54) second group animals 14) studied after sinoaortic denervation. A rat brain slice preparation then used exerts direct effect upon VLM. Perfusing over surface medullary slices evoked majority (39/49) graded relation magnitude stimulus. observed perfusion synaptic blockade medium. Retrograde labeling rhodamine tagged microspheres injected into thoracic intermediolateral cell column demonstrated sensitive located region projects spinal cord. These results demonstrate excited hypoxia; may play critical role hypoxia.