Respiratory sinus arrhythmia in freely moving and anesthetized rats.
Level 5 - mechanism / opinion, no new human data
Bench or animal research without human clinical data.
PubMed 15155710 · doi:10.1152/japplphysiol.00277.2004
What was done
Researchers measured respiratory sinus arrhythmia (RSA) in conscious, freely moving rats and tested the effects of three commonly used anesthetics: ketamine-xylazine (87 mg/kg and 13 mg/kg), pentobarbital sodium (60 mg/kg), and urethane (1 g/kg).
What was found
In conscious freely moving rats, heart rate significantly increased by 21 beats/min during inspiration. Under anesthesia, this pattern was altered: ketamine-xylazine depressed RSA, pentobarbital sodium abolished it, and urethane inverted RSA, causing heart rate to significantly decrease during inspiration.
Why it matters
This resolves a controversy by showing that conscious rats possess standard mammalian respiratory sinus arrhythmia, and that previously reported inverted RSA in rats is an artifact of urethane anesthesia.
Limits
The abstract does not state the sample size (n), sex, or strain of the animals, nor does it report exact numerical changes or confidence intervals for the anesthetized groups.
Cited by
- supports Vigorous inhales increase heart rate, while extended exhales decrease heart rate through respiratory sinus arrhythmia.