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Gender Differences in ECGs in 129/Sv Mice
Victor Chu, Adam Rosenthal, Jose M. Otero, Orlando Lopez, Ivo Amende, and Thomas G. Hampton; Mouse Specifics, Inc., Boston, MA. USA.
Web Published: July 1, 2001
Abstract
Although gender differences in cardiac function have been described in humans, gender differences in mouse physiology have not been extensively reported. Accordingly, we non-invasively recorded ECGs in conscious adult male (n=10) and female (n=10) 129/Sv mice. We found that female 129/Sv mice had significantly faster heart rates than males (689 ± 12 bpm vs. 571 ± 13 bpm, P<0.05). These data may be of interest to mouse-based studies of gene or drug pathways affecting regulation of heart rate.
Methods
Figure 1.Male ECG
Figure 2.Female ECG
129/Sv mice were obtained from The Jackson Laboratory (Bar Harbor, ME). The AnonyMOUSE TM ECG screening system (Mouse Specifics, Boston, MA) was used to record ECGs1. Each mouse was allowed to acclimate for 10 min prior to recording. Signals were collected at 2000 samples/s for at least 2 seconds to provide a continuous record of 20 to 30 beats. e-MOUSETM was used to interpret the signals. HR-corrected QT (QTc) was calculated via the method proposed by Mitchell et. al2.
Results
Table 1: Results
Males (n=10)
Females (n=10)
HR (bpm)
571 ± 13
689 ± 12*
QRS (ms)
9.6 ± 0.3
8.5 ± 0.1*
QT (ms)
70.2 ± 1.8
54.7 ± 2.0*
QTc (ms)
66.6 ± 1.9
58.4 ± 1.6*
*P < 0.05 via Student's 2-tail
t-test.
The study was completed within two hours. Neither anesthetic nor surgery was required. HR variability indices were comparable between males and females.
Discussion
We found significant gender differences in ECGS in 129/Sv mice, namely that females demonstrated heart rates ~ 20% faster than males. Gender differences in heart rate have been reported in rats3 and man4. Olsson et al. recently described contractile differences between male and female mice in a transgenic model of hypertrophic cardiomyopathy. Cross et al. reported6 that female mice demonstrated less severe myocardial stunning than males. Taken together, these observations further point to a role for sex hormones in modulating heart disease7.
References
Chu, V. et al. 2001. BMC Physiology 1:6.
Mitchell, G. F. et al. 1998. Am. J .Physiol. Heart Circ. Physiol. 247:H747-H751.
Chandler, M. P. & DiCarlo, S.E. 1998. Am. J. Physiol. Reg. Integ. Comp. Physiol. 43:R510-R516.
Huikuri, V.H. et al. 1996. Circulation 94:122-125.
Olsson, M.C. et al. 2001. Am J. Physiol. 280:H1136-H1144.
Cross, H.R. et al. 1998. Circ. Res. 83(12):1215-1223.
Huber, S.A. & Pfaeffle, B. 1994. J. Virol. 68:5126-5132.
