Arterial Baroreceptor Regulation of Peripheral Resistance and of Cardiac Performance

SUMMARY1. The feedback control of arterial blood pressure by the kidney in the range of hours was investigated in resting, conscious foxhounds.2. A servo-control device (connected to an aortic occlusive cuff implanted above both renal arteries) was used to maintain a constant pressure difference of 20 mmHg between aortic pressure measured proximal (mean arterial blood pressure: MAP) and distal (renal artery pressure: RAP) to the aortic cuff.3. Protocol 1 (n = 6) served as a 4 h time control without intervention, protocol 2 (n = 6) consisted of three periods: after a control of 20 min duration, the servocontrol device was activated for 180 min; this was followed by a recovery period of 40 min. Protocol 3 (n = 6) was as protocol 2, but during converting-enzyme inhibition.4. Servo-control increased plasma renin activity (PRA) transiently from 0 5 ng angiotensin I (AI)ml-l h-' to a peak value of 2-4 ng AI ml-' h-1, subsequently both RAP and MAP rose to reach a new steady state. During this increase in RAP, PRA declined to 1-4 ng AI ml-' h-1.5. On average, the compensation of the pressure decrease sensed by the kidney amounted to 63 % of the error signal (closed-loop gain of 0-63 + 0 1).6. Converting-enzyme inhibition reduced this closed-loop gain significantly (protocol 2 vs. protocol 3, 0-63+0'1 vs. 0-15+0 1; P < 0-05).7. It is concluded, that the kidney plays an important role in medium-term blood pressure regulation, most probably via the renin-angiotensin system.

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“…The closedloop gain was calculated as: Pdfrf/P1err. The open-loop gain corresponds to -G/(l -G0) (Scher, O'Leary & Sheriff, 1991).…”

Section: Data Handling and Statisticsmentioning

confidence: 99%

The role of the kidney in canine blood pressure control: direct assessment of the closed‐loop gain.

Persson

Ehmke

Kirchheim

et al. 1993

The Journal of Physiology

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“…In the present study, the lower NE concentrations in the HYPO group, coupled with marked differences in HR and AP, confirms that inadequate sympathetic outflow may be responsible for orthostatic intolerance in healthy elderly men. It is well documented that the arterial baroreceptors provide the critical regulation of AP during orthostatic stress [4], and that the unloading of arterial baroreceptors results in reflex increases in sympathetic outflow and decreases in parasympathetic activity [29]. Significant reductions in AP and PP, coupled with increases in HR have been suggested as evidence of arterial baroreceptor activation [30].…”

Section: Discussionmentioning

confidence: 99%

Norepinephrine and Epinephrine Responses during Orthostatic Intolerance in Healthy Elderly Men

Gabbett

Gass²,

Gass³

et al. 2000

Jpn.J.Physiol

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“…Distension of the vessels send an increasing frequency of action potentials to the Nucleus Tractus Solitarii (NTS) via CN IX, signaling an increase in mean arterial BP; alternatively, a decrease in BP decreases receptor activity until it stops altogether around 40 to 60 mmHg. Firing frequency is further increased by rapid increases in BP: twice as many action potentials are generated by an increasing pressure of 150 mmHg than a stationary pressure of 150 mmHg (Hall 2011, Scher et al 1991. The NTS responds to an increase in BP by inhibiting descending sympathetic efferents and exciting vagal efferents, causing both a decrease in HR and arterial vasoconstriction.…”

Section: Cardiovascular Regulationmentioning

confidence: 99%

“…BRS, also called "BRS gain," of significant sequences is measured by quantifying the change of RRI in response to changes in SBP to get the slope in ms/mmHg (Sagawa 2011). Despite the name, BRS slope does not reflect baroreceptor activity alone, but rather the integration of various reflex arcs that alter HR and vasoconstriction to maintain BP (including cardiopulmonary reflexes, baroreceptor reflexes, and the low-pressure receptors) (Scher et al 1991). Isolation of baroreceptor reflex activity requires either electrical or physical perturbation of the baroreceptors, a Valsalva maneuver, or pharmacological intervention (Hart et al 2010, Kamiya et al 2011, Vogel et al 2005.…”

Section: Evaluation Of Cardiovascular Function In Patients With Scimentioning

confidence: 99%

“…A baroreceptor effectiveness index (BEI) can be calculated by dividing the number of significant sequences by the total number of sequences (Parati et al 2000, Zollei et al 2003. Supine, BRS slope largely reflects the vagal relationship between SBP and RRI, as there is minimal sympathetic efferent vascular output beyond vasomotor tone (Scher et al 1991). While passively upright, however, the BRS measurements illustrate the increased sympathetic efferent activity to the heart and vasculature, as well as parasympathetic withdrawal (Blomqvist 2011).…”

Section: Evaluation Of Cardiovascular Function In Patients With Scimentioning

confidence: 99%

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Cardiovascular regulation and effects of respiratory motor training in patients with chronic spinal cord injury.

Ditterline¹

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Ditterline, Bonnie Legg, "Cardiovascular regulation and effects of respiratory motor training in patients with chronic spinal cord injury." (2015). December 2015This dissertation attempts to discover the mechanisms between cardiovascular and respiratory motor control post spinal cord injury (SCI): in normal, non-injured (NI) persons, cardiovascular regulation is dependent upon respiration, but there is nothing that suggests the mechanism for this relationship post-SCI. Thus we hoped to evaluate various aspects of cardiovascular regulation to further illustrate how this relationship is changed or unchanged by SCI.Chapter I describes the anatomy and physiology of the spine, respiratory system, and cardiovascular system in a NI person, and then describes how the function of these systems is changed by SCI. In addition, we describe therapies available to persons with SCI to treat or manage these dysfunctions. Briefly, cardiovascular function is dependent on respiration, and motor and sensory activity is partially mediated by the spine. Thus, SCI will impair respiratory and cardiovascular function because neurons from these respective systems vi originate within the spine. In addition to that, we hypothesize that SCI will further impair reflexes due to the dependence of cardiovascular regulation on respiration. This relationship has not been studied post-SCI, but it has great therapeutic potential.Chapter II details our specific aims and respective hypotheses: we think that poor respiration will exacerbate cardiovascular dysfunction (one) such that level and completeness will not correlate to cardiovascular functional outcomes (two); if hypotheses one and two are correct, then we hypothesize that we will be able to improve cardiovascular regulation by improving respiratory motor control.In Chapter III, we describe the methods and protocol by which we will either confirm or refute our respective hypotheses, including pulmonary and cardiovascular assessments, and statistical methods. Chapters IV, V, VI, and VII include our results and subsequent discussions, including validation of a particular method (Chapter IV); confirmation of cardiovascular impairment secondary to poor respiratory motor control (Chapter V); subsequent independence of functional outcomes and level of injury (Chapter VI); and improvements to cardiovascular regulation following improved respiratory motor control (Chapter VII).Finally, in Chapter VIII, we conclude that there is still dependence of cardiovascular function on respiration post-SCI, and describe the potential benefits that respiratory motor training can have on this population. In addition, vii we detail future directions as we pursue our goal of developing respiratory motor training into a standard of care in persons with SCI.

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Arterial Baroreceptor Regulation of Peripheral Resistance and of Cardiac Performance

Cited by 17 publications

References 149 publications

The role of the kidney in canine blood pressure control: direct assessment of the closed‐loop gain.

The role of the kidney in canine blood pressure control: direct assessment of the closed‐loop gain.

Norepinephrine and Epinephrine Responses during Orthostatic Intolerance in Healthy Elderly Men

Cardiovascular regulation and effects of respiratory motor training in patients with chronic spinal cord injury.

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