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Inhibition of Neuronal Nitric Oxide Reduces Heart Rate Variability in the Anaesthetised Dog
Author(s) -
Markos F.,
Snow H. M.,
Kidd C.,
Conlon K.
Publication year - 2001
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/eph8602257
Subject(s) - heart rate , nitric oxide , heart rate variability , medicine , cardiology , vagal tone , sinus (botany) , anesthesia , biology , blood pressure , botany , genus
In the vagally intact anaesthetised dog, we have investigated the role of nitric oxide (NO) on a normal sinus arrhythmia using an inhibitor of neuronally released NO, 1‐(2‐trifluoromethylphenyl) imidazole (TRIM). The mean and S.D. of the R‐R interval was used to describe mean heart rate and heart rate variability, respectively. TRIM (0.8 mg I.C.) injected into the sinus node artery increased the mean heart rate slightly but reduced heart rate variability 3‐fold from a control of 790 ± 124 ms (mean ± S.D.; n = 5) to 666 ± 36 ms (P < 0.01 Student's paired t test, n = 5). These results suggest that neuronally released NO may have a vagal facilitatory role in the maintenance of sinus arrhythmia in the normal heart.