Submitted on June 30, 2008
Revised on April 17, 2009
Accepted on April 18, 2009
Genetic influence on electrocardiogram time intervals and heart rate in aging mice
Shuqin Xing1, Shirng-Wern Tsaih1, Rong Yuan, Karen L. Svenson1, Linda Jorgenson1, Milly So1, Beverly Paigen1, and Ron Korstanje1*
1 The Jackson Laboratory
* To whom correspondence should be addressed. E-mail: ron.korstanje{at}jax.org.
Understanding the genetic influence on ECG time intervals and heart rate (HR) is important for identifying the genes underlying susceptibility to cardiac arrhythmias. The objective of this study was to determine the genetic influence on electrocardiogram parameters and their age-related changes in mice. ECGs were recorded in lead I on eight males and eight females from each of 28 inbred strains at the age of 6, 12 and 20 months. Significant inter-strain differences in P-R interval, QRS complex duration, and heart rate were found. Age-related changes in P-R interval, QRS complex duration, and heart rate differed among strains. P-R interval increased with age in 129S1/SvlmJ females, QRS complex duration decreased with age in C57BR/J males and DBA2/J females but increased in NON/ShiLtJ females. Heart rate decreased in C57L/J females and SM/J and P/J males but increased in BALB/cByJ males Differences between males and females were found for heart rate in SJL/J and in P-R interval in 129S1/SvlmJ. Broad-sense heritability estimates of electrocardiogram time intervals and heart rate ranged from 0.31 for QRS complex duration to 0.52 for P-R interval. Heritability estimates decreased with age for P-R. Our study revealed that genetic factors play a significant role on cardiac conduction activity, and age-related changes in electrocardiogram time intervals and heart rate.
