Interactions among reflex compensatory systems for posthemorrhage hypotension

Hara, Hiroshi; Katsuda, Shin-ichiro; Morita, Hironobu; Nishida, Yoshihiro; Koyama, Shozo

doi:10.1152/ajpheart.1986.250.6.h944

Cited by 14 publications

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“…Interactions between the carotid sinus and aortic baroreflexes have also been reported [22,23]. However, the present results indicate that a linear system analysis worked reasonably well when used to examine the system characteristics around the physiological operating pressure.…”

Section: Discussionmentioning

confidence: 49%

Closed-Loop Identification of Carotid Sinus Baroreflex Transfer Characteristics Using Electrical Stimulation.

Kawada

Sato²,

Inagaki³

et al. 2000

JJP

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Section: Discussionmentioning

confidence: 49%

Closed-Loop Identification of Carotid Sinus Baroreflex Transfer Characteristics Using Electrical Stimulation.

Kawada

Sato²,

Inagaki³

et al. 2000

JJP

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“…The input-output relationship determined by rapid mild hemorrhage can estimate the normal characteristics of the baroreflex system. In previous reports, the values for overall open-loop gain of the baroreflex system estimated by method of the rapid mild hemorrhage were 7.4 and 7.8 in anesthetized rabbits [11] and dogs [10] with pentobarbital sodium in intravenous doses of 27.5 and 35.0 mg/kg, respectively. These suggest that there is no remarkable difference between the two species in the overall AP control capacity of the baroreflex system in this dose range.…”

Section: Discussionmentioning

confidence: 94%

“…On the other hand, rapid mild hemorrhage is the withdrawal of a small amount of blood to allow us to do a precise physiological evaluation of baroreflex function [6,7,[9][10][11]13]. The MAP fall immediately after rapid mild hemorrhage (∆AP I ) is a transient fall in AP due to a small decrease in blood volume in the aorta.…”

Section: Discussionmentioning

confidence: 99%

Time-Dependent Change in Baroreflex Control Capacity of Arterial Pressure by Pentobarbital Anesthesia in Rabbits.

et al. 2000

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Abstract:The present study is designed to investigate the time-dependent effect of pentobarbital anesthesia on the baroreflex arterial pressure (AP) control system in rabbits. The overall AP control capacity of the baroreflex system was assessed with mean arterial pressure (MAP) responses to the rapid mild hemorrhage (2 ml/kg body weight) and an overall open-loop gain (G) of the system. The G value was determined by means of the following formula: G=∆AP I /∆AP S -1, where ∆AP I is an immediate MAP fall and ∆AP S a steady-state fall after the rapid hemorrhage. Prior to the experiment, two catheters for AP measurement and hemorrhage were chronically in-dwelt in the aortic arch via the left subclavian and left common carotid arteries, respectively. Control mean arterial pressure averaged for 30 sec before the rapid hemorrhage (CMAP), ∆AP I and ∆AP S significantly increased and reached the maximal value at 14 min (CAMP: p<0.01) and 28 min (∆AP I : p<0.01 and ∆AP S : p<0.01) after the intravenous injection of sodium pentobarbital in a 25.0 mg/kg dose, respectively. These values gradually decreased in the course of time and tended to recover to near the preanesthetic level at 77-98 min after the anesthesia. The G value significantly decreased from 7.3 in the conscious state to 1.5 at 28 min after the anesthesia (p<0.001), gradually increased with lapse of time and recovered to near the preanesthetic level at 77-98 min after the anesthesia. No significant difference in G was observed between in the conscious and anesthetized states beyond 70 min after the anesthesia (p>0.05). These findings suggest that pentobarbital sodium exerts a timedependent inhibitory effect on the baroreflex system but does not significantly affect the overall AP control capacity of the baroreflex system itself at least 70 min after the intravenous administration at a dose of 25.0 mg/kg.

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“…This assumption is based on linear analysis; the actual baroreflex system may only generate sustained oscillation, even with greater gain values, by virtue of system nonlinearity (14). Hosomi et al (5) reported that the total baroreflex gain estimated from AP response to mild hemorrhage was as great as 7 in rabbits. Because intravenous PBG halved the dynamic gain and increased the gain margin without affecting the phase characteristics, PBG could make the baroreflex system more stable.…”

Section: Reduction Of Dynamic Gain In Total Baroreflex Loop By Bj Reflexmentioning

confidence: 99%

Bezold-Jarisch reflex attenuates dynamic gain of baroreflex neural arc

Kashihara

Kawada²,

Yanagiya³

et al. 2003

American Journal of Physiology-Heart and Circulatory Physiology

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risch reflex attenuates dynamic gain of baroreflex neural arc. Am J Physiol Heart Circ Physiol 285: H833-H840, 2003. First published April 24, 2003 10.1152/ajpheart.01082. 2002-Although acute myocardial ischemia or infarction may induce the Bezold-Jarisch (BJ) reflex through the activation of serotonin receptors on vagal afferent nerves, the mechanism by which the BJ reflex modulates the dynamic characteristics of arterial pressure (AP) regulation is unknown. The purpose of this study was to examine the effects of the BJ reflex induced by intravenous phenylbiguanide (PBG) on the dynamic characteristics of the arterial baroreflex. In seven anesthetized rabbits, we perturbed intracarotid sinus pressure (CSP) according to a white noise sequence while renal sympathetic nerve activity (RSNA), AP, and heart rate (HR) were recorded. We estimated the transfer function from CSP to RSNA (neural arc) and from RSNA to AP (peripheral arc) before and after 10 min of intravenous administration of PBG (100 g ⅐ kg Ϫ1 ⅐ min Ϫ1 ). The intravenous PBG decreased mean AP from 84.5 Ϯ 4.0 to 68.2 Ϯ 4.7 mmHg (P Ͻ 0.01), mean RSNA to 76.2 Ϯ 7.0% (P Ͻ 0.05), and mean HR from 301.6 Ϯ 7.7 to 288.4 Ϯ 9.0 beats/min (P Ͻ 0.01). The intravenous PBG significantly decreased neural arc dynamic gain at 0.01 Hz (1.06 Ϯ 0.08 vs. 0.59 Ϯ 0.17, P Ͻ 0.05), whereas it did not affect that of the peripheral arc (1.20 Ϯ 0.12 vs. 1.18 Ϯ 0.41). In six different rabbits without intravenous PBG, the neural arc transfer function did not change between two experimental runs with intervening interval of 10 min, excluding the possibility that the cumulative effects of anesthetics had altered the neural arc transfer function. In conclusion, excessive activation of the BJ reflex during acute myocardial ischemia may exert an adverse effect on AP regulation, not only by sympathetic suppression, but also by attenuating baroreflex dynamic gain. renal sympathetic nerve activity; transfer function; systems analysis; rabbits; carotid sinus baroreflex THE CIRCULATORY SYSTEM has several mechanoreceptors and chemoreceptors in a variety of regions. The cardiopulmonary region is rich in such receptors. The most vagal afferent fibers from the cardiopulmonary receptors to the vasomotor center are classified as C fibers.Activation of the cardiopulmonary chemosensitive vagal afferent fibers reduces arterial pressure (AP), heart rate (HR), and cardiac output (31). These responses, mediated by 5-hydroxytryptamine (5-HT 3 ) serotonergic receptors on the cardiopulmonary vagal afferent fibers, are known as the Bezold-Jarisch (BJ) reflex (2, 7, 32). Although its physiological importance remains debatable, the BJ reflex could play a significant role in developing pathological responses associated with acute myocardial ischemia (19,20,24). Elucidating the effects of the BJ reflex on the circulatory regulation would be useful for better understanding the pathophysiology of ischemic heart diseases (16, 27). The BJ reflex can be induced chemically with pharmacological agents such as 5-HT and ...

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Interactions among reflex compensatory systems for posthemorrhage hypotension

Cited by 14 publications

References 0 publications

Closed-Loop Identification of Carotid Sinus Baroreflex Transfer Characteristics Using Electrical Stimulation.

Closed-Loop Identification of Carotid Sinus Baroreflex Transfer Characteristics Using Electrical Stimulation.

Time-Dependent Change in Baroreflex Control Capacity of Arterial Pressure by Pentobarbital Anesthesia in Rabbits.

Bezold-Jarisch reflex attenuates dynamic gain of baroreflex neural arc

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