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Carlos E Blanco - One of the best experts on this subject based on the ideXlab platform.
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Baroreceptor Reflex sensitivity in human neonates the effect of postmenstrual age
The Journal of Physiology, 2005Co-Authors: Peter Andriessen, Sidarto Bambang Oetomo, Chris H L Peters, Barbara Vermeulen, Pieter F F Wijn, Carlos E BlancoAbstract:We performed a cross-sectional study in human infants to determine if indices of R–R interval variability, systolic blood pressure (SBP) variability, and Baroreceptor Reflex sensitivity change with postmenstrual age (PMA: gestational age + postnatal age). The electrocardiogram, arterial SBP and respiration were recorded in clinically stable infants (PMA, 28–42 weeks) in the quiet sleep state in the first days after birth. (Cross-)spectral analyses of R–R interval series and SBP series were performed to calculate the power of low-frequency (LF, indicating Baroreceptor Reflex activity, 0.04–0.15 Hz) and high-frequency (HF, indicating parasympathetic activity, individualized between the p-10 and p-90 values of respiratory frequency) fluctuations, and transfer function phase and gain. The mean R–R interval, and LF and HF spectral powers of R–R interval series increased with PMA. The mean SBP increased with PMA, but not the LF and HF spectral powers of SBP series. In the LF range, cross-spectral analysis showed high coherence values (> 0.5) with a consistent negative phase shift between R–R interval and SBP, indicating a ∼3 s lag in R–R interval changes in relation to SBP. Baroreceptor Reflex sensitivity, calculated from LF transfer gain, increased significantly with PMA, from 5 (preterm) to 15 ms mmHg−1 (term). Baroreceptor Reflex sensitivity correlated significantly with the (LF and) HF spectral powers of R–R interval series, but not with the LF and HF spectral powers of SBP series. The principal conclusions are that Baroreceptor Reflex sensitivity and spectral power in R–R interval series increase in parallel with PMA, suggesting a progressive vagal maturation with PMA.
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Baroreceptor Reflex sensitivity in human neonates: the effect of postmenstrual age.
The Journal of physiology, 2005Co-Authors: Peter Andriessen, Sidarto Bambang Oetomo, Barbara Vermeulen, Pieter F F Wijn, Chris Peters, Carlos E BlancoAbstract:We performed a cross-sectional study in human infants to determine if indices of R-R interval variability, systolic blood pressure (SBP) variability, and Baroreceptor Reflex sensitivity change with postmenstrual age (PMA: gestational age+postnatal age). The electrocardiogram, arterial SBP and respiration were recorded in clinically stable infants (PMA, 28-42 weeks) in the quiet sleep state in the first days after birth. (Cross-)spectral analyses of R-R interval series and SBP series were performed to calculate the power of low-frequency (LF, indicating Baroreceptor Reflex activity, 0.04-0.15 Hz) and high-frequency (HF, indicating parasympathetic activity, individualized between the p-10 and p-90 values of respiratory frequency) fluctuations, and transfer function phase and gain. The mean R-R interval, and LF and HF spectral powers of R-R interval series increased with PMA. The mean SBP increased with PMA, but not the LF and HF spectral powers of SBP series. In the LF range, cross-spectral analysis showed high coherence values (>0.5) with a consistent negative phase shift between R-R interval and SBP, indicating a approximately 3 s lag in R-R interval changes in relation to SBP. Baroreceptor Reflex sensitivity, calculated from LF transfer gain, increased significantly with PMA, from 5 (preterm) to 15 ms mmHg-1 (term). Baroreceptor Reflex sensitivity correlated significantly with the (LF and) HF spectral powers of R-R interval series, but not with the LF and HF spectral powers of SBP series. The principal conclusions are that Baroreceptor Reflex sensitivity and spectral power in R-R interval series increase in parallel with PMA, suggesting a progressive vagal maturation with PMA.
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9 Baroreceptor Reflex Function in Newborns: The Effect of Postconceptional Age
Pediatric Research, 2005Co-Authors: Peter Andriessen, S. Bambang Oetomo, C.h.l. Peters, Guid Oei, Carlos E BlancoAbstract:Introduction: The Baroreceptor Reflex (BR) is the most prominent short-term compensator during blood pressure (BP) challenges.
Peter Andriessen - One of the best experts on this subject based on the ideXlab platform.
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Baroreceptor Reflex sensitivity in human neonates the effect of postmenstrual age
The Journal of Physiology, 2005Co-Authors: Peter Andriessen, Sidarto Bambang Oetomo, Chris H L Peters, Barbara Vermeulen, Pieter F F Wijn, Carlos E BlancoAbstract:We performed a cross-sectional study in human infants to determine if indices of R–R interval variability, systolic blood pressure (SBP) variability, and Baroreceptor Reflex sensitivity change with postmenstrual age (PMA: gestational age + postnatal age). The electrocardiogram, arterial SBP and respiration were recorded in clinically stable infants (PMA, 28–42 weeks) in the quiet sleep state in the first days after birth. (Cross-)spectral analyses of R–R interval series and SBP series were performed to calculate the power of low-frequency (LF, indicating Baroreceptor Reflex activity, 0.04–0.15 Hz) and high-frequency (HF, indicating parasympathetic activity, individualized between the p-10 and p-90 values of respiratory frequency) fluctuations, and transfer function phase and gain. The mean R–R interval, and LF and HF spectral powers of R–R interval series increased with PMA. The mean SBP increased with PMA, but not the LF and HF spectral powers of SBP series. In the LF range, cross-spectral analysis showed high coherence values (> 0.5) with a consistent negative phase shift between R–R interval and SBP, indicating a ∼3 s lag in R–R interval changes in relation to SBP. Baroreceptor Reflex sensitivity, calculated from LF transfer gain, increased significantly with PMA, from 5 (preterm) to 15 ms mmHg−1 (term). Baroreceptor Reflex sensitivity correlated significantly with the (LF and) HF spectral powers of R–R interval series, but not with the LF and HF spectral powers of SBP series. The principal conclusions are that Baroreceptor Reflex sensitivity and spectral power in R–R interval series increase in parallel with PMA, suggesting a progressive vagal maturation with PMA.
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Baroreceptor Reflex sensitivity in human neonates: the effect of postmenstrual age.
The Journal of physiology, 2005Co-Authors: Peter Andriessen, Sidarto Bambang Oetomo, Barbara Vermeulen, Pieter F F Wijn, Chris Peters, Carlos E BlancoAbstract:We performed a cross-sectional study in human infants to determine if indices of R-R interval variability, systolic blood pressure (SBP) variability, and Baroreceptor Reflex sensitivity change with postmenstrual age (PMA: gestational age+postnatal age). The electrocardiogram, arterial SBP and respiration were recorded in clinically stable infants (PMA, 28-42 weeks) in the quiet sleep state in the first days after birth. (Cross-)spectral analyses of R-R interval series and SBP series were performed to calculate the power of low-frequency (LF, indicating Baroreceptor Reflex activity, 0.04-0.15 Hz) and high-frequency (HF, indicating parasympathetic activity, individualized between the p-10 and p-90 values of respiratory frequency) fluctuations, and transfer function phase and gain. The mean R-R interval, and LF and HF spectral powers of R-R interval series increased with PMA. The mean SBP increased with PMA, but not the LF and HF spectral powers of SBP series. In the LF range, cross-spectral analysis showed high coherence values (>0.5) with a consistent negative phase shift between R-R interval and SBP, indicating a approximately 3 s lag in R-R interval changes in relation to SBP. Baroreceptor Reflex sensitivity, calculated from LF transfer gain, increased significantly with PMA, from 5 (preterm) to 15 ms mmHg-1 (term). Baroreceptor Reflex sensitivity correlated significantly with the (LF and) HF spectral powers of R-R interval series, but not with the LF and HF spectral powers of SBP series. The principal conclusions are that Baroreceptor Reflex sensitivity and spectral power in R-R interval series increase in parallel with PMA, suggesting a progressive vagal maturation with PMA.
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9 Baroreceptor Reflex Function in Newborns: The Effect of Postconceptional Age
Pediatric Research, 2005Co-Authors: Peter Andriessen, S. Bambang Oetomo, C.h.l. Peters, Guid Oei, Carlos E BlancoAbstract:Introduction: The Baroreceptor Reflex (BR) is the most prominent short-term compensator during blood pressure (BP) challenges.
Laguzzi Raul - One of the best experts on this subject based on the ideXlab platform.
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Serotonin2 receptors in the nucleus tractus solitarius: characterization and role in the Baroreceptor Reflex arc.
Cellular and molecular neurobiology, 2003Co-Authors: Laguzzi RaulAbstract:1. There is a general agreement concerning the key role of the Baroreceptor Reflex in blood pressure homeostasis. It is also well accepted that Baroreceptor afferent messages are first integrated within the nucleus tractus solitarius (NTS) and that an excitatory amino acid, probably glutamate, is the principal neurotransmitter of corresponding afferents fibers. However, important points concerning the processing of Baroreceptor messages within the NTS remain to be clarified, in particular the possible modulatory role of other neuroactive substances at this particular level in the medulla oblongata. 2. In this context, the present review focuses on serotonin, and the possible facilitatory influence of NTS serotonergic afferents and receptors on the Baroreceptor Reflex arc. Relevant pharmacological, electrophysiological, immunohistochemical, and biochemical data, are presented and discussed. They can be summarized as follows. 3. The selective destruction of the nodose ganglion-NTS serotonergic pathway produces a long-term increase in blood pressure variability, similar to that caused by Baroreceptor denervation. 4. Microinjection of picomolar doses of 5-HT into the NTS elicits the typical responses of Baroreceptor activation. 5. The cardiovascular effects elicited by local microinjections of specific agonists and antagonists into the NTS of intact rats and of animals that underwent nodose ganglionectomy indicate that the Baroreceptor-like effects of locally administered 5-HT are mediated by the activation of postsynaptic 5-HT2 receptors. 6. The medullary pathways which mediate NTS 5-HT2 receptor-evoked responses are similar to those involved in the Baroreceptor Reflex arc. 7. Pharmacological and electrophysiological studies suggest that the cardiovascular effects of intra-NTS 5-HT involve the 5-HT2A receptor subtype expressed by NTS barosensitive neurons that receive polysynaptic vagal afferents 8. Intra-NTS microinjection of a subthreshold dose of DOI, a 5-HT2 receptor agonist, which, on its own, does not produce any cardiovascular changes, significantly enhances the bradycardiac component of the baroReflex. 9. Altogether, the data summarized above show that, in the NTS, 5-HT acting at 5-HT2A receptors exerts a facilitatory influence on the Baroreceptor Reflex, especially on the cardiac component of this Reflex. 10. Convergent pharmacological and electrophysiological data indicate that, in the NTS, functional interactions between NMDA- and 5-HT2A-receptors coexpressed by the same neurons probably underlie the facilitatory influence of 5-HT upon the Baroreceptor Reflex. 11. Under physiological conditions, the 5-HT2A receptor-mediated facilitatory modulation of the cardiovagal component of the baroReflex might be triggered by 5-HT released from nodose ganglion-NTS serotoninergic afferent neurons and/or for serotoninergic projections originating in raphe nuclei. The latter possibility might notably occur during recovery after physical exercise and/or during the "freezing" reaction in stressed animals.
Hidefumi Waki - One of the best experts on this subject based on the ideXlab platform.
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Activation of histamine H1 receptors in the nucleus tractus solitarii attenuates cardiac Baroreceptor Reflex function in rats.
Acta physiologica (Oxford England), 2014Co-Authors: Miwa Takagishi, Masanobu Maeda, Sabine S. Gouraud, Mohammad Er Bhuiyan, Akira Kohsaka, Hidefumi WakiAbstract:Aim The nucleus tractus solitarii (NTS) is a central brainstem structure that plays an important role in regulating cardiovascular homeostasis. In this study, we examined whether H1 receptors in the NTS can control the Baroreceptor Reflex function by modulating synaptic transmission. Methods Cardiac Baroreceptor Reflex function was assessed before and after the microinjection of 2-pyridylethylamine (10–25 nmol), a histamine H1 receptor-specific agonist, into the NTS of urethane-anaesthetized Wistar rats. The cardiovascular responses induced by l-glutamate microinjection into the NTS were also examined before and after the NTS administration of 2-pyridylethylamine. Results Nucleus tractus solitarii microinjections of 2-pyridylethylamine significantly inhibited the gain of the cardiac Baroreceptor Reflex and bradycardiac/depressor responses induced by l-glutamate microinjection into the NTS. These findings suggest that histamine H1 receptors regulate the cardiac Baroreceptor Reflex in a post-synaptic manner to inhibit barosensitive NTS neurons. Conclusion Taken together with our previous findings, the present results provide further evidence that histamine may play a role within the NTS in regulating cardiovascular homeostasis.
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Chronic inhibition of standing behaviour alters Baroreceptor Reflex function in rats
Acta physiologica (Oxford England), 2008Co-Authors: Hidefumi Waki, Kiyoaki Katahira, Masao Yamasaki, Shin-ichiro Katsuda, Tsuyoshi Shimizu, Masanobu MaedaAbstract:Aim: To investigate whether daily orthostatic stress during development is an important factor affecting arterial Baroreceptor Reflex function, we examined the effect of chronic inhibition of upright standing behaviour on the Baroreceptor Reflex function in rats. Methods: Upright standing behaviour was chronically inhibited during the developmental period between 3 and 8 weeks of age in Sprague–Dawley rats and heart rate (HR) and aortic nerve activity in response to increased and decreased mean arterial pressure (MAP) was measured after the treatment period. Results: The Baroreceptor cardiac gain in the rats grown without standing behaviour was significantly lower than the control rats grown in a normal commercial cage (1.0 ± 0.1 beats min−1 mmHg−1 vs. 1.6 ± 0.2 beatsmin−1 mmHg−1, P
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Effects of spaceflight on postnatal development of arterial Baroreceptor Reflex in rats.
Acta physiologica Scandinavica, 2005Co-Authors: Hidefumi Waki, Kiyoaki Katahira, Masao Yamasaki, Tadanori Nagayama, Shin-ichiro Katsuda, Wago H, Toshiyasu Okouchi, H. O-ishi, M. Miyake, Y. MiyamotoAbstract:AIM It has been reported that spaceflight attenuates the arterial Baroreceptor Reflex. As this Reflex function changes dramatically during postnatal development, we hypothesized that space flight depresses the developmental changes of the Reflex system. To test this hypothesis, we evaluated the Baroreceptor Reflex function in rats, which were exposed to a microgravity environment on a space shuttle 9-25 days after birth. METHODS Baroreceptor Reflex sensitivity and the afferent sensitivity were evaluated by measuring heart rate (HR) and aortic nerve activity (ANA) changes in response to an increase in mean arterial pressure (MBP) derived by phenylephrine injection (20-50 microg kg(-1)) under urethane-anaesthesia. RESULTS Baroreceptor Reflex sensitivity (% change of HR/% change of MBP) was lower in the flight group (FLT: -0.19 +/- 0.04, n = 4) than either the asynchronous ground control group (AGC: -0.47 +/- 0.06, n = 6, P < 0.01) or the vivarium group (VIV: -0.41 +/- 0.07, n = 6, P < 0.05). This was similar to the differences of the afferent sensitivity (% change of ANA/% change of MBP) between FLT (2.07 +/- 0.30) and the control groups (AGC: 2.71 +/- 0.22, n.s.; VIV: 3.00 +/- 0.32, P < 0.05). At the end of 30 days of recovery under normal gravity conditions, however, there were no significant group differences in these parameters. conclusion: These results suggest that the space environment attenuates the postnatal development of the arterial Baroreceptor Reflex function in rats, which may be partially because of a depression of the postnatal development of the Baroreceptor afferents. These functional alterations, however, recover to their normal level on re-exposure to the Earth's gravity.
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dynamic exercise attenuates spontaneous Baroreceptor Reflex sensitivity in conscious rats
Experimental Physiology, 2003Co-Authors: Hidefumi Waki, Kiyoaki Katahira, Tsuyoshi Shimizu, Sergey Kasparov, David Murphy, Julian F R PatonAbstract:In humans, it has been reported that dynamic exercise attenuates spontaneous Baroreceptor Reflex sensitivity (sBRS), which is an index of the gain of the Baroreceptor–cardiac Reflex. We demonstrated previously that endogenously produced NO from endothelial nitric oxide synthase (eNOS) within the nucleus tractus solitarii (NTS), the central terminal site of Baroreceptor afferents, depressed sBRS. In this study, we investigated whether eNOS activity within the NTS plays any role in down-modulating the sBRS during dynamic exercise. In conscious Wistar rats arterial pressure and heart rate (HR) were monitored continuously and chronically using radiotelemetry before and during wheel cage running at 6 m min _1 for 10 min. sBRS was determined by a time-series method. During dynamic exercise systolic blood pressure (SBP) and HR were significantly increased (SBP: 138 ± 2 vs. 125 ± 2 mmHg, P < 0.001; HR: 447 ± 6 vs. 362 ± 8 beats min _1 , P < 0.001) while sBRS was significantly decreased (0.53 ± 0.03 vs. 1.08 ± 0.08 ms mmHg _1 , P < 0.001). In sino-aortic denervated rats the change in SBP in response to dynamic exercise was significantly larger than that in Baroreceptor-intact rats (denervated: 21.6 ± 2.5 mmHg; intact: 12.0 ± 2.8 mmHg, P < 0.05). In contrast, denervation made no difference to the change in HR. Although disabling eNOS activity in the NTS by adenoviral-directed expression of a dominant negative mutant form of eNOS increased resting sBRS (1.48 ± 0.20 vs. 1.09 ± 0.15 ms mmHg _1 , P < 0.05), the absolute level reached during dynamic exercise was identical to control. These results demonstrate that during dynamic exercise (i) the sBRS decreases around the operating point of the Baroreceptor–cardiac Reflex function curve in normotensive rats, (ii) the Baroreceptor Reflex operates to limit the rise in arterial pressure, and (iii) the attenuation of sBRS is not mediated by changes in eNOS activity within the NTS. Experimental Physiology (2003) 88.4, 517–526.
Irving H. Zucker - One of the best experts on this subject based on the ideXlab platform.
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Carotid sinus Baroreceptor Reflex in dogs with experimental heart failure.
Circulation research, 1991Co-Authors: Wei Wang, Jwo-sheng Chen, Irving H. ZuckerAbstract:We have previously demonstrated a decrease in Baroreceptor discharge sensitivity in dogs with experimental heart failure. In the present study, we determined the sensitivity of the carotid sinus Baroreceptor Reflex in dogs with pacing-induced heart failure. The carotid sinus Baroreceptor Reflex sensitivity was determined by pressurizing one carotid sinus with all other Baroreceptor and cardiopulmonary receptor inputs removed. The data were analyzed by plotting carotid sinus pressure-mean arterial pressure curves and carotid sinus pressure-renal sympathetic nerve activity curves in the two groups of dogs. The peak arterial pressure during carotid hypotension was significantly depressed in dogs with heart failure compared with normal dogs (107.1 +/- 5.7 versus 139.8 +/- 7.0 mm Hg, p less than 0.001). Mean arterial pressure range, renal sympathetic nerve activity range, and peak slope were significantly decreased in the heart-failure group. To determine if this depression was completely due to depression of Baroreceptor discharge per se, or to alterations in central or end-organ responsiveness, similar experiments were performed by stimulating the carotid sinus nerve and evaluating frequency, voltage, and duration of stimulation on the resultant mean arterial pressure and renal sympathetic nerve activity. As was the case with carotid sinus pressurization, electrical stimulation caused a significantly smaller change in mean arterial pressure in heart-failure dogs compared with the normal dogs. However, there was no significant difference between normal and heart-failure dogs for the renal sympathetic nerve activity-electrical stimulation curves. These data strongly suggest that the depressed carotid sinus Baroreceptor Reflex in heart failure is not solely the result of depressed Baroreceptor responsiveness but may be related to poor end-organ responses and normal central control of renal sympathetic outflow.