Lookup NU author(s): Dr Michelle Pierce
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Sympathetic activity is highly rhythmic in vivo. Some of this rhythmicity may originate in the spinal cord [Chizh BA, Headley PM, Paton JF (1998) J. Physiol. 508 (3): 907-18]. Here we show that field potential oscillations can indeed be generated in autonomic regions of spinal cord slices. 500μm transverse slices of thoracic spinal cord were cut from 10-12 day old, urethane-anaesthetised rats. Extracellular recordings from the IML were used to calculate power spectra of IML activity. Oscillations were quantified by measuring the spectral density at peak frequency. Ongoing rhythmic oscillations with a peak frequency of 8-20Hz were recorded from the IML of 40/95 slices. Spectral density of the oscillations was significantly increased by 10μM 5-HT (+91%, n=7), the 5-HT2 receptor agonist αmethyl5-HT (10μM; +156%, n=5), and the 5-HT2C receptor agonist MK212 (10μM; +259%, n=7). In addition, each of these agents induced oscillations in ≥2 previously arrhythmic slices. Both ongoing and drug-induced oscillations were attenuated by 1μM TTX (-74%, n=4) and by the gap junction blocker 18β-glycyrrhetinic acid (-61%, n=5). Our results show that sympathetic oscillations can be recorded from the IML of spinal cord slices. These rhythms are enhanced by activation of 5-HT receptors and are dependent on Na+ channels and electrical synapses.
Author(s): Pierce ML, Deuchars J, Deuchars SA
Publication type: Conference Proceedings (inc. Abstract)
Conference Name: FASEB Journal
Year of Conference: 2007