抄録
A major source of excitatory drive to the preganglionic sympathetic neurons originates from the rostral ventrolateral medulla (RVLM). RVLM sympathetic premotor neurons (RVLM neurons) receive an indirect input from peripheral chemoreceptors. However, it is still unclear whether RVLM neurons have chemosensitivity or not. We studied if RVLM sympathetic premotor neurons respond to hypercapnic (8% CO2)-hypoxia (5% O2) and sodium cyanide using an in situ arterially perfused preparation (the working heart-brainstem preparation). We recorded activities of the thoracic sympathetic chain and RVLM neurons. Finding that RVLM neurons continued to fire after switching to a low Ca2+ (0.2 mM)-high Mg2+ (5.25 mM) perfusate to block synaptic transmission is consistent with the hypothesis that they may have intrinsic pacemaker activity in absence of synaptic inputs. Since RVLM neurons were activated by hypercapnic-hypoxia and sodium cyanide after blockade of synaptic transmission, they may be directly sensitive to hypoxia and sodium cyanide. This study suggested that RVLM neurons can play a role of the central oxygen sensor and directly regulate the circulation of the blood according to the central oxygen level. [J Physiol Sci. 2008;58 Suppl:S48]
