Ventrolateral medulla and sympathetic chemoreflex in the rat

摘要: Splanchnic sympathetic nerve discharge (SND), phrenic activity (PND) and putative premotor neurons of the rostral ventrolateral medulla (RVL) were recorded in urethane-anesthetized vagotomized rats without aortic baroreceptor afferents. Carotid chemoreceptor stimulation with brief N2 inhalation increased SND by 101 +/- 7%, raised mean arterial pressure (MAP) rate RVL 46 12% (N = 32). During activation. most displayed pronounced central respiratory rhythmicity maximal firing probability immediately after cessation PND (postinspiratory phase) lowest during (inspiratory phase). Bilateral microinjection breed spectrum glutamate receptor antagonist kynurenic acid (Kyn, 5 nmol 100 nl) into blocked chemoreflex but left baroreflex intact. In contrast, bilateral same dose Kyn caudal (at obex level CVL) GABAA agonist muscimol (87.5 pmol 50 CVL produced effects identical to those Kyn. These results confirm that contains an essential relay demonstrate area plays no role chemoreflex. The data suggests these two reflexes could have a largely independent course through oblongata integration between information used for vasomotor control may occur as late neuronal stage RVL.