Abstract 1052: The Genetic Contribution To Heart Rate And Heart Rate Variability In Mice
Background. Measurements of heart rate (HR) and heart rate variability (HRV) have become increasingly useful clinical tools for assessment of autonomic nervous system function and cardiovascular health. However, a systematic examination of the genetic component to HR and HRV has not been performed. This study investigated the contribution of genetic background to variation in baseline HR and HRV in a wide range of inbred and recombinant inbred (RI) mouse strains by recording electrocardiographic (ECG) data under resting conditions.
Methods and Results. ECG data were recorded from thirty strains of inbred mice and twenty-nine RI strains. Significant differences in mean (± SEM) HR (bpm) were identified between inbred strains (range: 480.5 ± 11.4 (129Svlm) to 776.9 ± 11.5 (CAST); P < 0.001) and RI strains (range: 530.3 ± 38.1 (AXB8) to 719.5 ± 53.2 (BXA4). The mean (± SEM) range in total power (ms2/Hz) for the inbred strains was 1.39 ± 0.2 (PL) to 3.35 ± 0.1 (HeJ) (P < 0.01), and 1.46 ± 0.5 (AXB24) to 3.2 ± 0.2 (BXA4) (P < 0.001) for the RI strains. Multiple significant differences within the strain sets in total power and mean LF and HF power were also found. The strain distribution pattern (SDP) for HRV was not the same as the SDP for HR. Furthermore, the ratio between high frequency and low frequency components of HRV was not consistent between-strains. A significant QTL on chromosome 6 for HR and five suggestive QTLs on chromosomes 2, 4, 5, 6 and 10 for HRV were found using the RI strain data.
Conclusions. These results demonstrate a strong genetic component in the regulation of resting HR and HRV evidenced by the significant differences between-strains. Cross-over of the HR and HRV phenotypes in some strains suggests different sets of genes control the two phenotypes. Furthermore, the HR QTL contains the candidate gene Crhr2 which may be important in the genetic regulation of HR at rest.