Coherent sympathetic nerve activity in different postganglionic nerves after spinal cord transection in the cat

In this study, simultaneous discharges were recorded in three nerves originating from different levels of the spinal cord and the correlation between them was analyzed in the absence of the synchronizing input from the brainstem. In acute spinal cats, significant coherence (up to 0.3) was found at low frequencies (<4 Hz) between the vertebral and cardiac nerves and between the vertebral and renal nerves. Coherent discharges were, however, unstable, intermittent, and occurred rarely. In most experiments, it took several hours of observation to capture such an episode. Intrathecal glutamate injections facilitated the occurrence of rhythmic slow waves, which were, however, not correlated. We conclude that spinal sympathetic networks are capable of low frequency synchronization of the activity in different sympathetic outputs.