Author + information
Clinical evidence have shown that atrial fibrillation (AF) patients are associated with increased level of TNF-α. This study aimed to investigate the effects of TNF-α microinjection on the ganglionated plexi activity and on the AF inducibility.
In fourteen anaesthetised open-chest dogs, 0.5 ml TNF-α (5ug/ml) (Group 1, n=8) or saline (Group 2, n=6) was microinjected into anterior right ganglionated plexi (ARGP). At baseline and 30 min after TNF-α or saline microinjection, 40 ms of high frequency stimulation was delivered 2 ms after atrial pacing to determine the AF threshold at each atrial and pulmonary vein (PV) site. ARGP neural activity and ARGP function (determined by heart rate reduction in response to ARGP stimulation) were also measured before and after the microinjection. C-fos protein expressed in the ARGP was examined in 2 groups at the end of study.
In Group 1, when compared to baseline, microinjection of TNF-α significantly: (1) decreased AF threshold in all sites; (2) enhanced the sinus rate slowing response induced by ARGP stimulation; (3) increased the frequency and amplitude of the neural activity recorded from ARGP. However, in Group 2, there is no significant difference in these parameters before and after saline microinjection. In addition, the expression of c-fos protein was significantly higher in Group 1 than Group 2.
Microinjection of TNF-α into ARGP increases AF inducibility, probably by enhancing the neural activity of ARGP.