Intermittent hypoxia modulates nNOS expression and heart rate response to sympathetic nerve stimulation

2001 ◽  
Vol 281 (1) ◽  
pp. H132-H138 ◽  
Author(s):  
R. M. Mohan ◽  
S. Golding ◽  
D. J. Paterson
Keyword(s):  
Heart Rate ◽  
Nerve Stimulation ◽  
Sympathetic Nerve ◽  
Intermittent Hypoxia ◽  
Stellate Ganglion ◽  
No Synthase ◽  
Sympathetic Nerve Stimulation ◽  
Synthase Inhibitor ◽  
The Right ◽  
And Control

Nitric oxide (NO) decreases norepinephrine (NE) release and the heart rate (HR) response to sympathetic nerve stimulation (SNS). We tested the hypothesis that the enhanced HR response to sympathetic activation following chronic intermittent hypoxia (IH) results from a peripheral modulation of pacemaking by NO. Isolated guinea pig double atrial/right stellate ganglion preparations were studied from animals that had been exposed to IH ( n = 20) and control animals ( n = 22). The HR response to SNS was significantly enhanced in the IH group compared with the controls. However, the increase in HR with cumulative doses (0.1–10 μM) of bath-applied NE was similar in both groups. Western blot analysis showed less neuronal NO synthase in the right atria from the IH group. In IH animals, the NO synthase inhibitor, N ω-nitro-l-arginine (l-NNA; 100 μM) did not alter the increased HR response to SNS, whereas in control animals l-NNA significantly increased the HR response to SNS; an effect that was reversed with excess l-arginine. In conclusion, the enhanced HR response to SNS after IH may be related to a decreased inhibitory action of NO on presynaptic NE release.

Responses of atrium and ventricle to sustained sympathetic nerve stimulation

1991 ◽  
Vol 261 (6) ◽  
pp. H1889-H1894
Author(s):  
M. Furuyama ◽  
T. Haneda ◽  
J. Ikeda ◽  
T. Hiramoto ◽  
T. Sakuma ◽  
...  
Keyword(s):  
Nerve Stimulation ◽  
Sympathetic Nerve ◽  
Stellate Ganglion ◽  
Left Ventricular ◽  
Right Atrial ◽  
Control Group ◽  
Inotropic Response ◽  
Sympathetic Nerve Stimulation ◽  
Chronotropic Response ◽  
Control Value

To determine whether chronotropic and atrial inotropic responses to sympathetic nerve stimulation are maintained longer than ventricular inotropic response, the present study was performed with control and acute reserpinized dogs. We stimulated the right stellate ganglion of both groups supramaximally for 60 min and compared right atrial responses (chronotropism and inotropism) with left ventricular (LV) dP/dtmax. In the control group, heart rate (HR) immediately increased and was only slightly attenuated with 60 min of stimulation, and right atrial (RA) inotropic response was less attenuated than was LV response (7% in HR, 33% in RA dP/dtmax, 50% in LV dP/dtmax, P less than 0.01, from the peak value of each response). RA and LV norepinephrine (NE) content was decreased by the stimulation but remained higher than the LV control value. In the reserpinized group, NE content in the RA was low before the stimulation and was further decreased by the stimulation. In this group, HR response was attenuated (27% in HR, P less than 0.01) as was LV dP/dtmax, and the difference in contractile responsiveness between atrium and ventricle disappeared (58% in RA dP/dtmax vs. 61% in LV dP/dtmax, NS). The results indicate that the chronotropic response was only slightly attenuated and that the atrial contractile response was attenuated less than the ventricular response, with sustained sympathetic nerve stimulation in the normal heart. This can be ascribed to the much higher NE content in the RA than that in the LV.

Sympathetic changes during development of cardiac hypertrophy in aortic-constricted rats

1988 ◽  
Vol 255 (3) ◽  
pp. H452-H457 ◽  
Author(s):  
F. M. Siri
Keyword(s):  
Heart Rate ◽  
Cardiac Hypertrophy ◽  
Nerve Stimulation ◽  
Sympathetic Nerve ◽  
Time Course ◽  
Plasma Catecholamines ◽  
Pressure Overload ◽  
Left Ventricular ◽  
Sympathetic Nerve Stimulation ◽  
Norepinephrine Turnover

Cardiac hypertrophy is frequently associated with sympathetic changes that include increased myocardial norepinephrine turnover, depleted myocardial norepinephrine stores, decreased myocardial responses to sympathetic nerve stimulation, and elevated plasma catecholamines. To better understand these events mechanistically, the time course of each was assessed in rat hearts subjected to aortic constriction-induced pressure overload. There was no evidence of increased left ventricular norepinephrine turnover in abdominal aortic-constricted rats, when compared with sham-constricted animals, during the first 3 days postoperatively. Moreover, their turnover rate constants tended to be lower during this period, then increased significantly by day 7. Plasma catecholamines were increased and left ventricular norepinephrine stores were decreased only on day 7. Heart rate responses to maximal sympathetic nerve stimulation were significantly reduced on the third postoperative day. Thus the decrease in norepinephrine stores coincided with changes in left ventricular norepinephrine turnover and plasma catecholamines, whereas the reduction in heart rate responses did not. This pattern suggests an initial reflex decrease in myocardial sympathetic tone, followed by baroreceptor resetting, with an eventual increase in general sympathetic outflow. The period of increasing catecholamine stimulation occurred after a relative left ventricular hypertrophy had developed but before a significant increase in absolute left ventricular mass. Thus catecholamines may still importantly contribute to the hypertrophy seen in this model.

Dynamics of heart rate response to sympathetic nerve stimulation

1998 ◽  
Vol 275 (3) ◽  
pp. H995-H1001 ◽  
Author(s):  
Abdelkader Mokrane ◽  
Réginald Nadeau
Keyword(s):  
Heart Rate ◽  
Time Constant ◽  
Nerve Stimulation ◽  
Sympathetic Nerve ◽  
Neural Control ◽  
Sinus Node ◽  
Mean Delay ◽  
Norepinephrine Concentration ◽  
The Right

Electrical stimulation of the right cardiac sympathetic nerve was used to achieve a step increase of norepinephrine concentration at the sinus node. The heart rate (HR) response to sympathetic stimulation was characterized by a first-order process with a time delay. For moderate to high intensities of stimulation the mean delay and time constant were 0.7 and 2.1 s, respectively, and for low intensities of stimulation they were 0.4 and 1.1 s, respectively. From the analysis of the HR response to different patterns of nerve stimulation, in vivo neurotransmitter kinetics were estimated. The time constant of norepinephrine dissipation averaged ∼9 s. These results combined with computer simulations revealed two facets of sympathetic neural control of HR: 1) negligible role of the sympathetic system in beat-to-beat regulation of HR under stationary conditions and 2) ability of HR to react relatively quickly (within a few seconds) to sharp increases in sympathetic nerve traffic.

Absence of prejunctional sympathetic effect of amiodarone in hearts of open-chest anesthetized dogs

1990 ◽  
Vol 68 (2) ◽  
pp. 144-149 ◽  
Author(s):  
Daniel Lamontagne ◽  
Nobuharu Yamaguchi ◽  
Chantal Lambert ◽  
Jacques de Champlain ◽  
Réginald Nadeau
Keyword(s):  
Nerve Stimulation ◽  
Sympathetic Nerve ◽  
Random Order ◽  
Experimental Period ◽  
Treated Group ◽  
Left Ventricular ◽  
Sympathetic Nerve Stimulation ◽  
Open Chest ◽  
The Right ◽  
Na Release

The effect of amiodarone (30 mg/kg p.o. each day for 3 weeks) on noradrenaline (NA) overflow into coronary sinus (CS) blood during left stellate stimulation (15 V, 2-ms square waves, 30 s duration at 1, 2, 4, and 8 Hz in random order) was investigated in an open-chest dog preparation. CS blood samples were taken before and during the stimulation period for plasma NA and hematocrit determinations. CS blood flow was monitored (extracorporal circulation with an electromagnetic flow meter) and used for NA output computation. The right atrium was paced throughout the experimental period. However, because AV block occurred at a high pacing rate in some amiodarone-treated dogs, pacing rate was lower in that group than in control dogs (132 ± 13 vs. 161 ± 10 min−1, ns). Mean arterial pressure was also lower in the treated group (95 ± 9 vs. 110 ± 13 mmHg, ns) but increased in every dog upon stimulation (p < 0.05). Basal left ventricular dP/dtmax was comparable in the two groups of dogs and increased in a similar fashion upon stimulation (p < 0.05). The increase in plasma NA concentration upon stimulation was comparable between the control and the amiodarone-treated group (0.38 ± 0.08 vs. 0.40 ± 0.12 ng/mL at 1 Hz and 12.7 ± 3.1 vs. 11.3 ± 2.3 ng/mL at 8 Hz, ns). The increase in NA output was also comparable (7.0 ± 1.6 vs. 10.7 ± 5.4 ng/min at 1 Hz and 356 ± 124 vs. 334 ± 102 ng/min at 8 Hz, ns). Amiodarone did not alter the myocardial NA content. We conclude that amiodarone, administered orally for 3 weeks, does not interfere with neural NA release, or with the positive inotropic response, following sympathetic nerve stimulation in dogs.Key words: amiodarone, noradrenaline release, antiadrenergic effect, sympathetic nerve stimulation.

scholarly journals The effect of cardiac sympathetic nerve stimulation on the right ventricle in canine heart.

1987 ◽  
Vol 51 (5) ◽  
pp. 535-542 ◽  
Author(s):  
YUKIHIRO ABE ◽  
DAIJI SAITO ◽  
HIDEKI TANI ◽  
TAKAAKI NAKATSU ◽  
SHOZO KUSACHI ◽  
...  
Keyword(s):  
Right Ventricle ◽  
Nerve Stimulation ◽  
Sympathetic Nerve ◽  
Canine Heart ◽  
Cardiac Sympathetic Nerve ◽  
Sympathetic Nerve Stimulation ◽  
The Right

Cardiac sympathetic nerve stimulation does not attenuate dynamic vagal control of heart rate via α-adrenergic mechanism

2004 ◽  
Vol 287 (2) ◽  
pp. H860-H865 ◽  
Author(s):  
Tadayoshi Miyamoto ◽  
Toru Kawada ◽  
Yusuke Yanagiya ◽  
Masashi Inagaki ◽  
Hiroshi Takaki ◽  
...  
Keyword(s):  
Heart Rate ◽  
Nerve Stimulation ◽  
Sympathetic Nerve ◽  
Cardiac Sympathetic Nerve ◽  
Sympathetic Nerve Stimulation ◽  
Vagal Control ◽  
Adrenergic Mechanism

Interactive Effects of Verapamil and Sympathetic Nerve Stimulation on the Sinus and AV Nodes in the Canine Hearts.

1992 ◽  
Vol 33 (1) ◽  
pp. 83-93 ◽  
Author(s):  
Katsusuke YANO ◽  
Masanobu HIRATA ◽  
Takao MITSUOKA ◽  
Yoriaki MATSUMOTO ◽  
Tetsuya HIRATA ◽  
...  
Keyword(s):  
Nerve Stimulation ◽  
Sympathetic Nerve ◽  
Interactive Effects ◽  
Sympathetic Nerve Stimulation

scholarly journals The Cardiac Sympathetic Nerve Activity in the Elderly Is Attenuated in the Right Lateral Decubitus Position

2017 ◽  
Vol 3 ◽  
pp. 233372141770807 ◽  
Author(s):  
Konosuke Sasaki ◽  
Mayu Haga ◽  
Sarina Bao ◽  
Haruka Sato ◽  
Yoshikatsu Saiki ◽  
...  
Keyword(s):  
Heart Rate ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Lateral Decubitus Position ◽  
The Other ◽  
Elderly Adults ◽  
Nerve Activity ◽  
Left Lateral Decubitus Position ◽  
Lateral Decubitus ◽  
The Right

Objectives: The aim of this study was to evaluate the effect of the supine, left lateral decubitus, and right lateral decubitus positions on autonomic nervous activity in elderly adults by using spectral analysis of heart rate variability (HRV). Method: Forty-five adults aged 73.6 ± 5.7 years were enrolled. After lying in the supine position, all participants moved to the lateral decubitus positions in a random order and maintained the positions for 10 min, while electrocardiographic data were recorded to measure HRV. Results: The lowest heart rate continued for 10 min when participants were in the left lateral decubitus position compared with the other two positions ( p < .001), while the HRV indexes remained unchanged. The low-frequency HRV to high-frequency HRV ratio (LF/HF) for the right lateral decubitus position was significantly lower than that for the other positions. Discussion: The right lateral decubitus position may attenuate sympathetic nerve activity in elderly adults.

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