Fig 1.
After a 4-week adaptation to a 12-h/12-h LD cycle, Wistar rats were randomly divided into four groups (n = 20-21 per group) according to sex and period of the LD cycle, in which ECG parameters were measured following Zoletil 50 administration (i.p., 30 mg/kg; a combination of tiletamine-zolazepam; Virbac; France). Arrows represent ZT; i.e., the time of tiletamine-zolazepam administration relative to the beginning of the light period (ZT0) in the animal facility. Because lights were switched on at 06:00 (ZT0) and off at 18:00 (ZT12), experiments performed at 09:00 and 12:00 correspond to ZT3 and ZT6 during the light period and to ZT15 and ZT18 during the dark period in a reversed LD cycle where the light period began at 18:00 (ZT0) and ended at 06:00 (ZT12). LD cycle – light/dark cycle; ZT – Zeitgeber time. Created with BioRender.com.
Table 1.
Mean values of ECG parameters in Wistar rats under tiletamine-zolazepam anaesthesia with 95% confidence intervals.
Table 2.
Results of statistical analysis.
Table 3.
Key findings of the study.
Fig 2.
Effect of tiletamine-zolazepam on HR in Wistar rats depending on sex and LD cycle.
Differences in HR are presented as individual data points, with columns representing the mean ± SD for each group (white column – light period of the LD cycle; grey column – dark period of the LD cycle). Asterisks indicate the level of statistical significance according to Sidak’s post hoc test: *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001. HR – heart rate.
Fig 3.
Effect of tiletamine-zolazepam on the atrial complex in Wistar rats depending on sex and LD cycle.
Differences in (A) PR interval duration and (B) P wave amplitude are presented as individual data points, with columns representing the mean ± SD for each group (white column – light period of the LD cycle; grey column – dark period of the LD cycle). Asterisks indicate the level of statistical significance according to Sidak’s post hoc test: *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001.
Fig 4.
Effect of tiletamine-zolazepam on the ventricular complex in Wistar rats depending on sex and LD cycle.
Differences in (A) QRS interval, (B) QT interval, (C) QTc interval, (D) R wave amplitude, and (E) T wave amplitude are presented as individual data points, with columns representing the mean ± SD for each group (white column – light period of the LD cycle; grey column – dark period of the LD cycle). Asterisks indicate the level of statistical significance according to Sidak’s post hoc test: *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001.