Factors influencing baseline electrocardiographic parameters in rats: A systematic review of experimental studies published from 1960 to the present

Figures

• 

  FIGURE 1. Flow diagram constructed in accordance with the PRISMA 2020 guidelines (Page et al., 2021). ECG, electrocardiography; SD, Sprague–Dawley; WKY, Wistar or Wistar/Kyoto.

• 

  FIGURE 2. Electrocardiographic parameters in male WKY and SD rats, regardless of the anesthesia used. Differences in (a) HR (nWKY = 125; nSD = 70), (b) PR (PQ) interval (nWKY = 98; nSD = 42), (c) QRS interval (nWKY = 114; nSD = 58), (d) QT interval (nWKY = 106; nSD = 59), and (e) QTc interval (nWKY = 73; nSD = 31) between WKY and SD rats are shown as gray data points representing individual extracted mean values from available studies, with a black straight line indicating group means ± standard deviation. Statistically significant results according to the unpaired nonparametric Mann–Whitney test are indicated by bolded p values. bpm, beats per minute; HR, heart rate; ms, milliseconds; SD, Sprague–Dawley; WKY, Wistar or Wistar/Kyoto.

• 

  FIGURE 3. Electrocardiographic parameters in female WKY and SD rats, regardless of the anesthesia used, highlighting the underrepresentation of female cohorts in experimental studies. Differences in (a) HR (nWKY = 4; nSD = 6), (b) PR (PQ) interval (nWKY = 2; nSD = 5), (c) QRS complex (nWKY = 3; nSD = 2), (d) QT interval (nWKY = 3; nSD = 4), and (e) QTc interval (nWKY = 4; nSD = 1) between WKY and SD rats are shown as gray data points representing individually extracted mean values from available studies, with the black line indicating group means ± standard deviation. bpm, beats per minute; HR, heart rate; ms, milliseconds; SD, Sprague–Dawley; WKY, Wistar or Wistar/Kyoto.

• 

  FIGURE 4. Electrocardiographic parameters in male WKY and SD rats under the most commonly used anesthetic protocols. Differences in (a) HR, (b) PR (PQ) interval, (c) QRS complex, (d) QT interval, and (e) QTc interval under various anesthetics categorized into broader groups as defined in the methodology (CON, BAR, ETH, KET, URE, and INH) are shown as data points (black points – WKY strain; gray points – SD strain) representing individual extracted mean values from available studies, with a black straight line indicating group means ± standard deviation. For clarity, the number of extracted means per group is reported in Table 6. Black bolded p values indicate significant strain‐dependent differences (nonparametric Mann–Whitney test), whereas orange bolded p values indicate significant differences between anesthetic groups within the WKY or SD strain (Dunn's post hoc test following the nonparametric Kruskal–Wallis test). BAR, barbital; bpm, beats per minute; CON, conscious rats; ETH, ether; HR, heart rate; INH, inhalation anesthesia; KET, ketamine; ms, milliseconds; SD, Sprague–Dawley; URE, urethane; WKY, Wistar or Wistar/Kyoto.