Coherent rhythmic discharges in sympathetic nerves supplying thermoregulatory circulations in the rat.
1. In anaesthetised rats, activity recorded from sympathetic postganglionic neurones innervating the tail circulation has characteristic rhythmicity (0.4-1.2 Hz). At the population level this rhythmicity can be seen as a peak (T-peak) in autospectra of sympathetic activity recorded from ventral collector nerves (VCNs). 2. Here we investigated whether nerves supplying thermoregulatory circulations share common rhythmic discharges at T-peak frequency. Activity was recorded from nerve pairs consisting of left ventral collector nerve (LVCN) and one of the following: right ventral collector nerve (RVCN), left dorsal collector nerve (DCN), left saphenous nerve (SN) or left renal nerve (RN). 3. During central apnoea, T-peak frequencies in RVCN autospectra were similar to those of simultaneously recorded LVCN and these activities were coherent. Similar observations were made for nerve pairs involving LVCN-DCN and LVCN-SN. In contrast, autospectra of RN activity did not contain T-peaks. 4. In comparison to the peaks in autospectra of RN activity, when the frequency of rhythmic phrenic nerve activity was manipulated T-peaks in VCN, DCN and SN autospectra did not show obligatory 1:1 locking. 5. We conclude that T-peaks are a robust feature of autospectra of sympathetic discharges supplying thermoregulatory circulation but not those influencing the kidney. The high coherence demonstrated between the T-peak discharges is consistent with the view that common/coupled oscillators located within the CNS influence cutaneous vasoconstrictor sympathetic activity.
Smith
J E
JE
Autonomic Neuroscience Institute, Department of Physiology, Royal Free and University College Medical School, University College London, London NW3 2PF, UK.
Gilbey
M P
MP
D000818:Animals; D001049:Apnea / Q000097:blood / Q000503:physiopathology; D001784:Blood Gas Analysis; D001833:Body Temperature Regulation / Q000502:physiology*; D016014:Linear Models; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D010507:Periodicity; D010791:Phrenic Nerve / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017779:Sympathetic Fibers, Postganglionic / Q000502:physiology*; D013623:Tail / Q000098:blood supply / Q000294:innervation* / Q000502:physiology*