Abstract
The relative role of parasympathetic, sympathetic, and ventilatory influences in the genesis of blood pressure and R-R interval variability is controversial. In 13 freely behaving WKY rats instrumented with venous and arterial catheters and chest electrodes, mean arterial pressure (MAP, mmHg), R-R interval (ms), and respiratory fluctuations were monitored for 90 min in the control condition and after intravenous atropine (0.75 mg/kg) and/or propranolol (1 mg/kg). Spectral power (pw) in the 0.25- to 0.75-Hz (midfrequency, MF) and the 0.75- to 3.0-Hz (high-frequency, HF, respiratory- synchronous) bands was computed in sequences of 400 heartbeats by use of a combined autoregressive analysis. Atropine reduced but did not abolish HF R- R interval pw (from 1.73 ± 0.50 to 0.39 ± 0.27 ms 2, P <0.01) and halved HF MAP pw (from 0.41 ± 0.30 to 0.21 ± 0.12 mmHg 2, P <0.05), whereas propranolol did not affect HF pw of the R-R interval or MAP. Propranolol also failed to significantly modify MF R-R interval pw (from 0.48 ± 0.44 to 0.40 ± 0.34 ms 2, P = NS) or MF MAP pw (from 0.54 ± 0.39 to 0.42 ± 0.20 mmHg 2, P = NS), whereas atropine virtually abolished MF R-R interval pw (from 0.48 ± 0.44 to 0.01 ± 0.01 ms 2, P <0.01) and also significantly reduced MF MAP pw (from 0.54 ± 0.39 to 0.33 ± 0.24 mmHg 2, P <0.01). The effects of combined blockade were similar to those of atropine alone. It is concluded that, in the unanesthetized rat, efferent vagal influences are responsible for a large fraction of HF R-R interval power, but a sizable amount of such fluctuations persists after atropine and has a ventilatory, rather than an efferent vagal, origin. Vagal influences also contribute to HF MAP power. Vagal (but not sympathetic) influences are important determinants of MF R-R interval fluctuations and also contribute significantly to MF MAP fluctuations.
| Original language | English |
|---|---|
| Journal | American Journal of Physiology - Heart and Circulatory Physiology |
| Volume | 269 |
| Issue number | 5 38-5 |
| Publication status | Published - 1995 |
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Keywords
- atropine
- mean arterial pressure
- propranolol
- R-R interval
- spectral power
ASJC Scopus subject areas
- Physiology
Cite this
Autonomic and ventilatory components of heart rate and blood pressure variability in freely behaving rats. / Perlini, S.; Giangregorio, F.; Coco, M.; Radaelli, A.; Solda, P. L.; Bernardi, L.; Ferrari, A. U.
In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 269, No. 5 38-5, 1995.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Autonomic and ventilatory components of heart rate and blood pressure variability in freely behaving rats
AU - Perlini, S.
AU - Giangregorio, F.
AU - Coco, M.
AU - Radaelli, A.
AU - Solda, P. L.
AU - Bernardi, L.
AU - Ferrari, A. U.
PY - 1995
Y1 - 1995
N2 - The relative role of parasympathetic, sympathetic, and ventilatory influences in the genesis of blood pressure and R-R interval variability is controversial. In 13 freely behaving WKY rats instrumented with venous and arterial catheters and chest electrodes, mean arterial pressure (MAP, mmHg), R-R interval (ms), and respiratory fluctuations were monitored for 90 min in the control condition and after intravenous atropine (0.75 mg/kg) and/or propranolol (1 mg/kg). Spectral power (pw) in the 0.25- to 0.75-Hz (midfrequency, MF) and the 0.75- to 3.0-Hz (high-frequency, HF, respiratory- synchronous) bands was computed in sequences of 400 heartbeats by use of a combined autoregressive analysis. Atropine reduced but did not abolish HF R- R interval pw (from 1.73 ± 0.50 to 0.39 ± 0.27 ms 2, P <0.01) and halved HF MAP pw (from 0.41 ± 0.30 to 0.21 ± 0.12 mmHg 2, P <0.05), whereas propranolol did not affect HF pw of the R-R interval or MAP. Propranolol also failed to significantly modify MF R-R interval pw (from 0.48 ± 0.44 to 0.40 ± 0.34 ms 2, P = NS) or MF MAP pw (from 0.54 ± 0.39 to 0.42 ± 0.20 mmHg 2, P = NS), whereas atropine virtually abolished MF R-R interval pw (from 0.48 ± 0.44 to 0.01 ± 0.01 ms 2, P <0.01) and also significantly reduced MF MAP pw (from 0.54 ± 0.39 to 0.33 ± 0.24 mmHg 2, P <0.01). The effects of combined blockade were similar to those of atropine alone. It is concluded that, in the unanesthetized rat, efferent vagal influences are responsible for a large fraction of HF R-R interval power, but a sizable amount of such fluctuations persists after atropine and has a ventilatory, rather than an efferent vagal, origin. Vagal influences also contribute to HF MAP power. Vagal (but not sympathetic) influences are important determinants of MF R-R interval fluctuations and also contribute significantly to MF MAP fluctuations.
AB - The relative role of parasympathetic, sympathetic, and ventilatory influences in the genesis of blood pressure and R-R interval variability is controversial. In 13 freely behaving WKY rats instrumented with venous and arterial catheters and chest electrodes, mean arterial pressure (MAP, mmHg), R-R interval (ms), and respiratory fluctuations were monitored for 90 min in the control condition and after intravenous atropine (0.75 mg/kg) and/or propranolol (1 mg/kg). Spectral power (pw) in the 0.25- to 0.75-Hz (midfrequency, MF) and the 0.75- to 3.0-Hz (high-frequency, HF, respiratory- synchronous) bands was computed in sequences of 400 heartbeats by use of a combined autoregressive analysis. Atropine reduced but did not abolish HF R- R interval pw (from 1.73 ± 0.50 to 0.39 ± 0.27 ms 2, P <0.01) and halved HF MAP pw (from 0.41 ± 0.30 to 0.21 ± 0.12 mmHg 2, P <0.05), whereas propranolol did not affect HF pw of the R-R interval or MAP. Propranolol also failed to significantly modify MF R-R interval pw (from 0.48 ± 0.44 to 0.40 ± 0.34 ms 2, P = NS) or MF MAP pw (from 0.54 ± 0.39 to 0.42 ± 0.20 mmHg 2, P = NS), whereas atropine virtually abolished MF R-R interval pw (from 0.48 ± 0.44 to 0.01 ± 0.01 ms 2, P <0.01) and also significantly reduced MF MAP pw (from 0.54 ± 0.39 to 0.33 ± 0.24 mmHg 2, P <0.01). The effects of combined blockade were similar to those of atropine alone. It is concluded that, in the unanesthetized rat, efferent vagal influences are responsible for a large fraction of HF R-R interval power, but a sizable amount of such fluctuations persists after atropine and has a ventilatory, rather than an efferent vagal, origin. Vagal influences also contribute to HF MAP power. Vagal (but not sympathetic) influences are important determinants of MF R-R interval fluctuations and also contribute significantly to MF MAP fluctuations.
KW - atropine
KW - mean arterial pressure
KW - propranolol
KW - R-R interval
KW - spectral power
UR - http://www.scopus.com/inward/record.url?scp=0028847117&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0028847117&partnerID=8YFLogxK
M3 - Article
VL - 269
JO - American Journal of Physiology
JF - American Journal of Physiology
SN - 0363-6119
IS - 5 38-5
ER -