1. Recruitment of cardiac parasympathetic activity: effects of clonidine on cardiac vagal motoneurones, pressure lability, and cardiac baroreflex slope in rats 
E. Toader, A. Cividjian, L. Quintin 
British Journal of Anaesthesia 
Volume 102, Issue 3, Pages (March 2009)
DOI: /bja/aen390
Copyright © 2009 British Journal of Anaesthesia Terms and Conditions

2. Fig 1
Identification of CVMs. (a) CVM spontaneous action potential. (b) Antidromic identification from cardiac vagal branch: collision test with a stimulus triggered at 8 ms (top four traces) and 7.5 ms (bottom four traces) after a spontaneous spike (left side of traces). The CVM gives a constant-latency, antidromic spike for an 8 ms delay. The depolarization is cancelled by the orthodromic spike when the delay is 7.5 ms (left side of bottom four traces: positive collision test), indicative of positive antidromic identification. (c) Orthodromic identification (barosynchronicity): upper trace shows an arterial pulse-triggered histogram constructed from the spontaneous activity of the CVM shown in (a) and (b) (1224 cycles, 20 ms bins), and the pulse wave (lower trace). (d) Coronal hemisection of rat medulla. Dots show the localization of some CVM: ×, −4.3 mm interaural (obex defined as the junction of the central canal with the i.v. ventricle: not shown); ♦, −4.68 mm (plate from Paxinos’ atlas46); Δ, −5 mm; o, −5.3 mm.
British Journal of Anaesthesia  , DOI: ( /bja/aen390)
Copyright © 2009 British Journal of Anaesthesia Terms and Conditions

3. Fig 2
Typical traces of RR interval (top), CVM activity (middle), and SBP (bottom) in one animal following atenolol 2 mg kg−1 (a) and clonidine 100 μg kg−1 i.v. (b). Note the reduction in pressure lability, increase in CVM activity, and increase in sinus arrhythmia after clonidine.
British Journal of Anaesthesia  , DOI: ( /bja/aen390)
Copyright © 2009 British Journal of Anaesthesia Terms and Conditions

4. Fig 3
Effect of atenolol 2 mg kg−1 i.v. on circulatory parameters, CVM unit activity, and derived data [mean (sem)]. (a) SBP; (b) RR interval; (c) sd of SBP; (d) sd of RR interval; (e) firing rate; (f) cardiac baroreflex analysed at the CVM level (SBP–CVM slope; pressure–unit relationship); (g) cardiac baroreflex analysed at the heart level (SBP–RR interval slope; pressure–RR interval relationship). P<0.05.
British Journal of Anaesthesia  , DOI: ( /bja/aen390)
Copyright © 2009 British Journal of Anaesthesia Terms and Conditions

5. Fig 4
Effect of cumulative doses of clonidine 10–100 μg kg−1 i.v. following pretreatment with atenolol 2 mg kg i.v. followed by infusion of 2 mg kg−1 h−1 [mean (sem)]. (a) SBP; (b) RR interval (n=10 rats); (c) sd of SBP; (d) sd of RR interval; (e) CVMs firing rate (n=7 cells; thick line: raw data; dashed line: data normalized for SBP); (f) slope of cardiac baroreflex analysed at the CVM level (SBP–CVM slope; pressure–unit relationship); (g) slope of the cardiac baroreflex analysed at the heart level (SBP–RR interval slope; pressure–RR interval relationship). *P<0.05 at the considered interval.
British Journal of Anaesthesia  , DOI: ( /bja/aen390)
Copyright © 2009 British Journal of Anaesthesia Terms and Conditions