Do natriuretic peptides modify arterial baroreflexes in sheep?

Thomas, Colleen J.; Woods, Robyn L.

doi:10.1113/expphysiol.2004.028233

Cited by 3 publications

(3 citation statements)

References 40 publications

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“…The majority of these experiments were performed with infusion of ANP leading to 10-20 fold increases in plasma concentrations of ANP. A study using only moderate doses of the natriuretic peptides in sheep showed no effect on arterial baroreflex sensitivity [42]. Consequently, the relatively minor differences between eprosartan and placebo in the concentrations of ANP and BNP probably play no major role in the proposed change in the function of the arterial baroreflex in our study.…”

Section: Discussioncontrasting

confidence: 50%

Eprosartan modulates the reflex activation of the sympathetic nervous system in sodium restricted healthy humans

Vase

Lauridsen

Bech

et al. 2008

Brit J Clinical Pharma

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WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• A sympatho-inhibitory effect of ACE-inhibitors and AT1 receptor antagonists has been widely demonstrated in animal models, but in humans this effect tends only to be present during chronic treatment in conditions with pre-existing high levels of sympathetic activity.• Sodium restriction increases renal sympathetic nerve activity and the activity of the renin-angiotensin system and may be a favourable condition to demonstrate sympatho-inhibition as a short-term effect of the AT1 receptor antagonist eprosartan in healthy humans. WHAT THIS STUDY ADDS• Results from our study indicate that during sodium restriction eprosartan has a small inhibitory effect on nonbaroreflex mediated activation of the sympathetic nervous system. • During arterial baroreflex mediated activation of the sympathetic nervous system this effect is, however, completely overruled by an increased sensitivity of the arterial baroreflex. AIMSTo test the hypothesis that eprosartan inhibits both nonbaroreflex and arterial baroreflex mediated activation of the sympathetic nervous system, assessed by renal tubular function, systemic haemodynamics and vasoactive hormones, in sodium restricted healthy humans. METHODSThe effect of eprosartan on urinary sodium, lithium and water excretion, heart rate (HR), blood pressure and vasoactive hormones was measured before, during and after a cold pressor test (CPT) and sodium nitroprusside (SNP) infusion in a randomized, placebo controlled, double-blind, crossover study in 17 healthy subjects. Glomerular filtration rate and renal tubular function were determined by a continuous infusion clearance technique and vasoactive hormones by radioimmunoassays. RESULTSEprosartan attenuated the impact of the CPT on HR (mean difference from placebo (95% confidence interval) (3.9 (0.7, 7.0) min) and mean arterial pressure (MAP) (4.7 (0.3, 9.2) mmHg), but no effect of eprosartan was observed on the impact of the CPT on renal tubular function. During a SNP induced reduction in MAP of 10 mmHg eprosartan decreased fractional excretions of sodium (0.46 (0.14, 0.76)%) and lithium (5.1 (2.5, 7.6)%) and tended to increase HR (4.1 (-0.26, 8.4) min -1 ) and plasma concentrations of norepinephrine (33.8 (-5.8, 72.1) pg ml CONCLUSIONSThese findings suggest that during mild sodium restriction eprosartan has a small inhibitory effect on nonbaroreflex mediated activation of the sympathetic nervous system. During arterial baroreflex mediated activation of the sympathetic nervous system this effect is, however, completely overruled by an increased sensitivity of the arterial baroreflex.

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Section: Discussioncontrasting

confidence: 50%

Eprosartan modulates the reflex activation of the sympathetic nervous system in sodium restricted healthy humans

Vase

Lauridsen

Bech

et al. 2008

Brit J Clinical Pharma

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“…The site of this action of BNP and the other natriuretic peptides has been inferred to be on cardiac afferents. The reasons for this are that BNP enhances von Bezold-Jarisch (23) and high pressure, ramp cardiac mechanoreceptor reflexes (27) but, at the same doses, is without effect on steady-state (principally arterial) baroreflexes (26). Also in keeping with a cardiac rather than arterial origin of this effect is the observation that the ability of ANP to enhance ramp mechanoreceptor and von Bezold-Jarisch reflexes was still evident in rats after sinoaortic denervation (22).…”

Section: Discussionmentioning

confidence: 48%

“…This action is mediated by particulate guanylate cyclase (pGC) receptors (25), but their location is as yet uncertain. On the one hand, experiments on rats and sheep have found that BNP, in a dose that enhanced the von BezoldJarisch and "ramp" (cardiac) baroreflex, did not alter the bradycardic response to arterial baroreceptor loading [as assessed by the steady-state baroreceptor reflex (26,27)]. These findings have been interpreted as showing modulation specifically of reflexes from the heart, with cardiac afferents being the most likely site of hormone action, echoing early studies on ANP (1,28).…”

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confidence: 65%

Effect of systemic B-type natriuretic peptide on cardiac vagal motoneuron activity

Toader

McAllen

Cividjian³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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Toader E, McAllen RM, Cividjian A, Woods RL, Quintin L. Effect of systemic B-type natriuretic peptide on cardiac vagal motoneuron activity. Am J Physiol Heart Circ Physiol 293: H3465-H3470, 2007. First published September 28, 2007; doi:10.1152/ajpheart.00528.2007.-Intravenous B-type natriuretic peptide (BNP) enhances the bradycardia of reflexes from the heart, including the von Bezold-Jarisch reflex, but its site of action is unknown. The peptide is unlikely to penetrate the blood-brain barrier but could act on afferent or efferent reflex pathways. To investigate the latter, two types of experiment were performed on urethane-anesthetized (1.4 g/kg iv) rats. First, the activity was recorded extracellularly from single cardiac vagal motoneurons (CVMs) in the nucleus ambiguus. CVMs were identified by antidromic activation from the cardiac vagal branch and by their barosensitivity. Phenyl biguanide (PBG), injected via the right atrium in bolus doses of 1-5 g to evoke the von Bezold-Jarisch reflex, caused a dose-related increase in CVM activity and bradycardia. BNP infusion (25 pmol ⅐ kg Ϫ1 ⅐ min Ϫ1 iv) significantly enhanced both the CVM response to PBG (n ϭ 5 rats) and the reflex bradycardia, but the log-linear relation between those two responses over a range of PBG doses was unchanged by BNP. The reflex bradycardia was not enhanced in five matched time-control rats receiving only vehicle infusions. In five other rats the cervical vagi were cut and the peripheral right vagus was stimulated supramaximally at frequencies of 1-20 Hz. The bradycardic responses to these stimuli were unchanged before, during, and after BNP infusion. We conclude that systemic BNP in a moderate dose enhances the von Bezold-Jarisch reflex activation of CVM, in parallel with the enhanced reflex bradycardia. That enhancement is due entirely to an action before the vagal efferent arm of the reflex pathway.cardiopulmonary; von Bezold-Jarisch; phenyl biguanide; bradycardia; heart; chemoreflex; parasympathetic; vagus; single unit activity INCREASED SYMPATHETIC DRIVE and reduced vagal activity are prognostic of a poor outcome in cardiovascular disease (12,14,29). Many studies have shown the benefits of reducing sympathetic activity in cardiovascular disease (10), but actions on the vagal arm of autonomic nervous system have been underexploited. It is likely that enhancing vagal drive to the heart will be beneficial because efferent vagal stimulation can improve the outcome after myocardial infarction in dogs (29). Mechanisms that may enhance vagal tone are therefore of interest for their therapeutic potential in cardiovascular disease.The cardiac natriuretic peptides-atrial natriuretic peptide (ANP), B-and C-type natriuretic peptides (BNP and CNP)-have actions that may be interpreted as cardioprotective (31). Indeed, BNP (Nesiritide) has proved clinically useful in the treatment of congestive heart failure (5, 16). One of these presumed cardioprotective actions is to enhance bradycardic reflexes such as the von Bezold-Jarisch (cardiopulmonary) ch...

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Characterization of baroreflex gain in the domestic pigeon (Columba livia)

Lucitti

Hedrick

2006

Comparative Biochemistry and Physiology Part A: Molecular &

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Do natriuretic peptides modify arterial baroreflexes in sheep?

Cited by 3 publications

References 40 publications

Eprosartan modulates the reflex activation of the sympathetic nervous system in sodium restricted healthy humans

Eprosartan modulates the reflex activation of the sympathetic nervous system in sodium restricted healthy humans

Effect of systemic B-type natriuretic peptide on cardiac vagal motoneuron activity

Characterization of baroreflex gain in the domestic pigeon (Columba livia)

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