Heart rate dynamics in monoamine oxidase-A- and -B-deficient mice.
Heart rate (HR) dynamics were investigated in mice deficient in monoamine oxidase A and B, whose phenotype includes elevated tissue levels of norepinephrine, serotonin, dopamine, and phenylethylamine. In their home cages, spectral analysis of R-R intervals revealed more pronounced fluctuations at all frequencies in the mutants compared with wild-type controls, with a particular enhancement at 1-4 Hz. No significant genotypic differences in HR variability (HRV) or entropies calculated from Poincaré plots of the R-R intervals were noted. During exposure to the stress of a novel environment, HR increased and HRV decreased in both genotypes. However, mutants, unlike controls, demonstrated a rapid return to baseline HR during the 10-min exposure. Such modulation may result from an enhanced vagal tone, as suggested by the observation that mutants responded to cholinergic blockade with a decrease in HRV and a prolonged tachycardia greater than controls. Monoamine oxidase-deficient mice may represent a useful experimental model for studying compensatory mechanisms responsible for changes in HR dynamics in chronic states of high sympathetic tone.
Holschneider
D P
DP
Department of Psychiatry and the Behavioral Sciences, University of Southern California, Keck School of Medicine, Los Angeles 90089, USA. holschne@hsc.usc.edu
Scremin
O U
OU
Chialvo
D R
DR
Chen
K
K
Shih
J C
JC
D000818:Animals; D001522:Behavior, Animal; D004562:Electrocardiography; D005838:Genotype; D006024:Glycopyrrolate / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008995:Monoamine Oxidase / Q000172:deficiency* / Q000235:genetics / Q000502:physiology; D009043:Motor Activity; D018727:Muscarinic Antagonists / Q000494:pharmacology; D013312:Stress, Physiological / Q000503:physiopathology; D014630:Vagus Nerve / Q000187:drug effects / Q000503:physiopathology
D018727:Muscarinic Antagonists; D008995:Monoamine Oxidase; D006024:Glycopyrrolate