Uniformity in dynamic baroreflex regulation of left and  right cardiac sympathetic nerve activities

Kawada, Toru; Uemura, Kazunori; Kashihara, Koji; Jin, Yin-Tie; Li, Meihua; Zheng, Can; Sugimachi, Masaru; Sunagawa, Kenji

doi:10.1152/ajpregu.00736.2002

Cited by 16 publications

(14 citation statements)

References 20 publications

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“…One rationale for using splanchnic SNA is that the splanchnic region has been regarded as a major site for the blood flow redistribution [17,30]. Furthermore, we have continued to observe insignificant differences in the steady-state responses to CSP between left and right cardiac SNAs [31], between cardiac and renal SNAs [32], and among cardiac, renal, and muscle SNAs [33] in anesthetized rabbits. It seems that the carotid sinus baroreflex brings about common activity in addition to regional activity among sympathetic nerves innervating several districts (see Appendix 3).…”

Section: Equilibrium Diagram and Simulation Studymentioning

confidence: 63%

Open-loop dynamic and static characteristics of the carotid sinus baroreflex in rats with chronic heart failure after myocardial infarction

Kawada

Kamiya

et al. 2010

J Physiol Sci

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We estimated open-loop dynamic characteristics of the carotid sinus baroreflex in normal control rats and chronic heart failure (CHF) rats after myocardial infarction. First, the neural arc transfer function from carotid sinus pressure to splanchnic sympathetic nerve activity (SNA) and its corresponding step response were examined. Although the steady-state response was attenuated in CHF, the negative peak response and the time to peak did not change significantly, suggesting preserved neural arc dynamic characteristics. Next, the peripheral arc transfer function from SNA to arterial pressure (AP) and its corresponding step response were examined. The steady-state response and the initial slope were reduced in CHF, suggesting impaired end-organ responses. In a simulation study based on the dynamic and static characteristics, the percent recovery of AP was reduced progressively as the size of disturbance increased in CHF, suggesting that a reserve for AP buffering is lost in CHF despite relatively maintained baseline AP.

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Section: Equilibrium Diagram and Simulation Studymentioning

confidence: 63%

Open-loop dynamic and static characteristics of the carotid sinus baroreflex in rats with chronic heart failure after myocardial infarction

Kawada

Kamiya

et al. 2010

J Physiol Sci

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“…Sinoaortic denervation and vagotomy were performed bilaterally to minimize reflex changes in efferent sympathetic nerve activity. The left and right cardiac sympathetic nerves were exposed using a midline thoracotomy and sectioned (16). In the vagal stimulation group, a pair of bipolar stainless steel wire electrodes was attached to the cardiac end of the sectioned right vagal nerve for stimulation.…”

Section: Methodsmentioning

confidence: 99%

Angiotensin II disproportionally attenuates dynamic vagal and sympathetic heart rate controls

Kawada

Mizuno²,

Shimizu

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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To better understand the pathophysiological role of angiotensin II (ANG II) in the dynamic autonomic regulation of heart rate (HR), we examined the effects of intravenous administration of ANG II (10 microg.kg(-1).h(-1)) on the transfer function from vagal or sympathetic nerve stimulation to HR in anesthetized rabbits with sinoaortic denervation and vagotomy. In the vagal stimulation group (n = 7), we stimulated the right vagal nerve for 10 min using binary white noise (0-10 Hz). The transfer function from vagal stimulation to HR approximated a first-order low-pass filter with pure delay. ANG II attenuated the dynamic gain from 7.6 +/- 0.9 to 5.8 +/- 0.9 beats.min(-1).Hz(-1) (means +/- SD; P < 0.01) without affecting the corner frequency or pure delay. In the sympathetic stimulation group (n = 7), we stimulated the right postganglionic cardiac sympathetic nerve for 20 min using binary white noise (0-5 Hz). The transfer function from sympathetic stimulation to HR approximated a second-order low-pass filter with pure delay. ANG II slightly attenuated the dynamic gain from 10.8 +/- 2.6 to 10.2 +/- 3.1 beats.min(-1).Hz(-1) (P = 0.049) without affecting the natural frequency, damping ratio, or pure delay. The disproportional suppression of the dynamic vagal and sympathetic regulation of HR would result in a relative sympathetic predominance in the presence of ANG II. The reduced high-frequency component of HR variability in patients with cardiovascular diseases, such as myocardial infarction and heart failure, may be explained in part by the peripheral effects of ANG II on the dynamic autonomic regulation of HR.

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“…The fourvariable sigmoidal logistic function (described above) was fitted to the dynamic changes in MAP and ƒ H. The min and max ƒH, B, and C values were determined for each injection response and were then averaged across the injections to produce mean values for each embryo. This method represented a simple derivative of previous studies that used mathematical modeling to examine dynamic beatto-beat changes in ƒ H (52) and sympathetic nerve activity (25)(26)(27) in adult mammals.…”

Section: Methodsmentioning

confidence: 99%

ANG II and baroreflex control of heart rate in embryonic chickens (Gallus gallus domesticus)

Mueller

Burggren

Crossley

2013

American Journal of Physiology-Regulatory, Integrative and Comp

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Mueller CA, Burggren WW, Crossley II DA. ANG II and baroreflex control of heart rate in embryonic chickens (Gallus gallus domesticus). Am J Physiol Regul Integr Comp Physiol 305: R855-R863, 2013. First published September 4, 2013 doi:10.1152/ajpregu.00298.2013.-ANG II alters the short-term blood pressure buffering capacity of the baroreflex in many adult animals. In embryonic chickens, high plasma ANG II levels contribute to baseline mean arterial pressure (MAP, kPa) without changing heart rate (ƒH, beats/min). We hypothesized, on the basis of these features, that an ANG II-induced reduction in baroreflex sensitivity is present in embryonic chickens as in adults. We examined baroreflex function in day 19 embryonic chickens (Gallus gallus domesticus) after chronic depletion of endogenous ANG II via angiotensinconverting enzyme (ACE) inhibition with captopril (5 mg/kg) from days 5-18 of incubation. The correlation between MAP and ƒH was assessed using increasing doses of sodium nitroprusside, a vasodilator, and phenylephrine, a vasoconstrictor. We used two analytical methods to evaluate baroreflex function: a conventional "static" method, in which maximal MAP and ƒH responses were examined, and a "dynamic" method that assessed beat-to-beat changes during the response to pharmacological manipulation. Captopril-treated embryos were hypotensive by 19% with baroreflex slopes ϳ40% steeper and normalized gains ϳ50% higher than controls, and differences across treatments were similar using either analytical method. Furthermore, reintroduction of ANG II via infusion raised MAP back to control levels and decreased the baroreflex gain in captopril-treated embryos. Therefore, during typical chicken development, ANG II dampens the baroreflex regulatory capacity and chicken embryos can be used as a natural model of elevated ANG II for studying developmental cardiovascular function. This study is the first to demonstrate that reduction of embryonic ANG II alters normal baroreflex function.angiotensin-converting enzyme inhibitor; blood pressure; ANG II infusion; sodium nitroprusside; phenylephrine THE BAROREFLEX IS AN IMPORTANT compensatory mechanism that mitigates short-term changes in arterial pressure. Peripheral limb motor outputs adjust vascular resistance, and cardiac limb motor outputs adjust arterial pressure via heart rate (ƒ H , beats/ min) (37). In the case of the cardiac limb, this negative feedback loop produces an inverse relationship between arterial pressure and ƒ H . Barostatic reflexes are functional during the fetal and adult phases of life, with clear function demonstrated from ϳ60% of development in fetal sheep (5,32,46,49), from ϳ80% of incubation in embryonic chickens (1, 15), and from ϳ70% of incubation in embryonic American alligators (Alligator mississippiensis) (12). The common conclusion from each of these investigations is that baroreflex function is an important homeostatic mechanism during fetal or embryonic life. However, modulation of baroreflex function via systemic hormones and central neurope...

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Uniformity in dynamic baroreflex regulation of left and right cardiac sympathetic nerve activities

Cited by 16 publications

References 20 publications

Open-loop dynamic and static characteristics of the carotid sinus baroreflex in rats with chronic heart failure after myocardial infarction

Open-loop dynamic and static characteristics of the carotid sinus baroreflex in rats with chronic heart failure after myocardial infarction

Angiotensin II disproportionally attenuates dynamic vagal and sympathetic heart rate controls

ANG II and baroreflex control of heart rate in embryonic chickens (Gallus gallus domesticus)

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