Abstract
The relative contributions of a central neural oscillator and of the delay in α-adrenergic transmission within the baroreflex loop in the predominance of low-frequency (LF) cardiovascular variability during sympathetic activation in humans are unclear. We measured R-R interval (RR), muscle sympathetic nerve activity (MSNA), blood pressure (BP), and their variability in 10 normal subjects during sympathetic activation achieved by BP lowering with sodium nitroprusside (SNP) and α-adrenergic blockade using phentolamine. SNP and phentolamine induced comparable reductions in BP (P > 0.25). Despite tachycardia and sympathetic activation with both SNP and phentolamine, LF variability in RR, MSNA, and BP increased during SNP and decreased during phentolamine (SNP: RR +20 ± 6%, MSNA +3 ± 5%, systolic BP +9 ± 6%, diastolic BP +7 ± 5%; phentolamine: RR -2 ± 7%, MSNA -34 ± 6%, systolic BP -16 ± 8%, diastolic BP -13 ± 4%, P <0.05 except systolic BP, where P = 0.09). Thus LF variability is reduced when sympathetic activation is induced by α-adrenergic blockade. This suggests that α-adrenergic transmission within the baroreflex loop may contribute importantly to the predominance of LF cardiovascular variability associated with sympathetic excitation in humans.
| Original language | English |
|---|---|
| Journal | American Journal of Physiology - Heart and Circulatory Physiology |
| Volume | 281 |
| Issue number | 2 50-2 |
| Publication status | Published - 2001 |
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Keywords
- Sympathetic nervous system
ASJC Scopus subject areas
- Physiology
- Physiology (medical)
Cite this
Contrasting effects of phentolamine and nitroprusside on neural and cardiovascular variability. / Van De Borne, Philippe; Rahnama, Mohsen; Mezzetti, Silvia; Montano, Nicola; Porta, Alberto; Degaute, Jean Paul; Somers, Virend K.
In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 281, No. 2 50-2, 2001.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Contrasting effects of phentolamine and nitroprusside on neural and cardiovascular variability
AU - Van De Borne, Philippe
AU - Rahnama, Mohsen
AU - Mezzetti, Silvia
AU - Montano, Nicola
AU - Porta, Alberto
AU - Degaute, Jean Paul
AU - Somers, Virend K.
PY - 2001
Y1 - 2001
N2 - The relative contributions of a central neural oscillator and of the delay in α-adrenergic transmission within the baroreflex loop in the predominance of low-frequency (LF) cardiovascular variability during sympathetic activation in humans are unclear. We measured R-R interval (RR), muscle sympathetic nerve activity (MSNA), blood pressure (BP), and their variability in 10 normal subjects during sympathetic activation achieved by BP lowering with sodium nitroprusside (SNP) and α-adrenergic blockade using phentolamine. SNP and phentolamine induced comparable reductions in BP (P > 0.25). Despite tachycardia and sympathetic activation with both SNP and phentolamine, LF variability in RR, MSNA, and BP increased during SNP and decreased during phentolamine (SNP: RR +20 ± 6%, MSNA +3 ± 5%, systolic BP +9 ± 6%, diastolic BP +7 ± 5%; phentolamine: RR -2 ± 7%, MSNA -34 ± 6%, systolic BP -16 ± 8%, diastolic BP -13 ± 4%, P <0.05 except systolic BP, where P = 0.09). Thus LF variability is reduced when sympathetic activation is induced by α-adrenergic blockade. This suggests that α-adrenergic transmission within the baroreflex loop may contribute importantly to the predominance of LF cardiovascular variability associated with sympathetic excitation in humans.
AB - The relative contributions of a central neural oscillator and of the delay in α-adrenergic transmission within the baroreflex loop in the predominance of low-frequency (LF) cardiovascular variability during sympathetic activation in humans are unclear. We measured R-R interval (RR), muscle sympathetic nerve activity (MSNA), blood pressure (BP), and their variability in 10 normal subjects during sympathetic activation achieved by BP lowering with sodium nitroprusside (SNP) and α-adrenergic blockade using phentolamine. SNP and phentolamine induced comparable reductions in BP (P > 0.25). Despite tachycardia and sympathetic activation with both SNP and phentolamine, LF variability in RR, MSNA, and BP increased during SNP and decreased during phentolamine (SNP: RR +20 ± 6%, MSNA +3 ± 5%, systolic BP +9 ± 6%, diastolic BP +7 ± 5%; phentolamine: RR -2 ± 7%, MSNA -34 ± 6%, systolic BP -16 ± 8%, diastolic BP -13 ± 4%, P <0.05 except systolic BP, where P = 0.09). Thus LF variability is reduced when sympathetic activation is induced by α-adrenergic blockade. This suggests that α-adrenergic transmission within the baroreflex loop may contribute importantly to the predominance of LF cardiovascular variability associated with sympathetic excitation in humans.
KW - Sympathetic nervous system
UR - http://www.scopus.com/inward/record.url?scp=0034887854&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034887854&partnerID=8YFLogxK
M3 - Article
C2 - 11454557
AN - SCOPUS:0034887854
VL - 281
JO - American Journal of Physiology
JF - American Journal of Physiology
SN - 0363-6119
IS - 2 50-2
ER -