[Role of sympathetic nervous system on blood pressure and heart rate variabilities in the rat: spectral analysis].
The role of the sympathetic nervous system (SNS) in the genesis of the beat-to-beat variability of blood pressure (BP) and heart rate (HR) was studied using spectral analysis. The SNS activity of genetically normotensive rats of the Lyon strain (LN) was abolished in 2 ways: 1) adrenergic blockade with administrations of phentolamine (PHE, 5 mg/kg i.v.) or propranolol (PRO, 5 mg/kg i.v.) or both drugs (PHEPRO) or 2) destruction of the sympathetic fibers with an early chronic treatment with guanethidine (LNSx). HR and systolic (SBP) and diastolic (DBP) BP spectra were computed using 50 to 100 stationary sequences from 1 h beat-to-beat recordings and covered the 0.015-3.85 Hz frequency band. In LN rats, spectra obtained in baseline conditions exhibited a high-frequency peak (HF, 1.04-1.13 Hz) related to the respiratory frequency and a mid-frequency peak (MF, 0.38-0.45 Hz). Concerning BP, the alterations of the SNS induced significant decreases of the total modulus (mmHg/Hz1/2) of the MF band (0.27-0.74 Hz): [formula: see text] In addition, the MF peak of SBP and DBP spectra was abolished in LNSx and PHEPRO rats. Concerning HR spectra, the moduli of all the frequency components were decreased in PHEPRO rats only. In conclusion, the similarity of the results observed in LNSx and PHEPRO rats shows that the MF oscillations of BP depend in a large extent (65%) on the action of the sympathetic fibers and involve the activation of both alpha- and beta-adrenoceptors. Concerning DBP, this effect is especially mediated by the activation of alpha-adrenoceptors.(ABSTRACT TRUNCATED AT 250 WORDS)
Cerutti
C
C
CNRS URA 606, Département de physiologie et pharmacologie clinique, Lyon.
Lo
M
M
Julien
C
C
Paultre
C Z
CZ
Vincent
M
M
Sassard
J
J
D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D008297:Male; D051381:Rats; D011941:Receptors, Adrenergic / Q000502:physiology; D013057:Spectrum Analysis; D013564:Sympathetic Nervous System / Q000502:physiology*
D011941:Receptors, Adrenergic
Rôle du système nerveux sympathique dans la variabilité de la pression artérielle et de la fréquence cardiaque chez le rat: étude par analyse spectrale.