Strain-specific patterns of autonomic nervous system activity and heart failure susceptibility in mice

Transgenic mice are widely used to study cardiac function, but strain-dependent differences in autonomic nervous system activity (ANSA) have not been explored. We compared 1) short-term pharmacological responses of cardiac rhythm in FVB vs. C57Black6/SV129 wild-type mice and 2) long-term physiological dynamics of cardiac rhythm and survival in tumor necrosis factor (TNF)-alpha transgenic mice with heart failure (TNF-alpha mice) on defined backgrounds. Ambulatory telemetry electrocardiographic recordings and response to saline, adrenergic, and cholinergic agents were examined in FVB and C57Black6/SV129 mice. In FVB mice, baseline heart rate (HR) was higher and did not change after injection of isoproterenol or atropine but decreased with propranolol. In C57Black6/SV129 mice, HR did not change with propranolol but increased with isoproterenol or atropine. Mean HR, but not indexes of HR variability, was an excellent predictor of response to autonomic agents. The proportion of surviving animals was higher in TNF-alpha mice on an FVB background than on a mixed FVB/C57Black6 background. The homeostatic states of ANSA are strain specific, which can explain the interstrain differences in mean HR, pharmacological responses, and survival of animals with congestive heart failure. Strain-specific differences should be considered in selecting the strains of mice used for transgenic and gene targeting experiments.