AUGMENTED RENAL SYMPATHETIC-NERVE ACTIVITY BY CENTRAL COMMAND DURING OVERGROUND LOCOMOTION IN DECEREBRATE CATS

We examined whether the cerebrum is essential for producing the rapid autonomic adjustment at the onset of spontaneous overground locomotion . Renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP ), heart rate (HR), and electromyogram of the forelimb triceps brachia lis were measured when freely moving, decerebrate cats spontaneously p roduced overground locomotion, supporting body weight. Decerebration w as performed at the level of the precollicular-premammillary body. RSN A increased 95 +/- 14 impulses/s (68 +/- 10% of baseline value) at the onset of spontaneous locomotion, which was followed by rises in MAP a nd HR (7 +/- 1 mmHg and 18 +/- 2 beats/min, respectively). Concomitant ly with the MAP rise, RSNA declined toward control values and then inc reased again during the subsequent period of locomotion. The same rapi d increase in RSNA at the onset of locomotion was observed after sinoa ortic denervation and vagotomy. It is concluded that some central site (s), other than the cerebrum and the rostral part of the diencephalon, can generate the centrally induced autonomic adjustment at the onset of spontaneous overground locomotion, which is independent of arterial baroreceptor and vagal afferents.