ANP, BNP, and CNP enhance bradycardic responses to cardiopulmonary chemoreceptor activation in  conscious sheep

We demonstrated previously that atrial natriuretic peptide (ANP) enhances reflex bradycardia to intravenous serotonin [5-hydroxytryptamine (5-HT)] (von Bezold-Jarisch reflex) in rats. To determine whether 1) ANP affects this cardiopulmonary vagal reflex in another species and 2) B-type (BNP) and C-type (CNP) natriuretic peptides share with ANP the ability to modulate this reflex, we used intravenous phenylbiguanide (PBG), a 5-HT3agonist, as the stimulus to evoke a von Bezold-Jarisch reflex (dose-related, reproducible bradycardia) in conscious adult sheep ( n = 5). Three doses of PBG (13 ± 3, 20 ± 3, and 31 ± 4 μg/kg) injected into the jugular vein caused reflex cardiac slowing of −7 ± 1, −15 ± 2, and −36 ± 3 beats/min, respectively, under control conditions. These doses of PBG were repeated during infusions of ANP, BNP, or CNP (10 pmol · kg−1 · min−1 iv), or vehicle (normal saline). Each of the natriuretic peptides significantly ( P < 0.05) enhanced the sensitivity of bradycardic responses to PBG by 94 ± 8% (ANP), 142 ± 55% (BNP), and 61 ± 16% (CNP). Thus not only did ANP sensitize cardiopulmonary chemoreceptor activation in a species with resting heart rate close to that in humans, but BNP and CNP also enhanced von Bezold-Jarisch reflex activity in conscious sheep.

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Medullary pathways mediating the parasubthalamic nucleus depressor response

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00437.2007 ◽

2008 ◽

Vol 294 (4) ◽

pp. R1276-R1284 ◽

Cited By ~ 13

Author(s):

John Ciriello ◽

L. Pastor Solano-Flores ◽

M. Patricia Rosas-Arellano ◽

Gilbert J. Kirouac ◽

Tanja Babic

Keyword(s):

Heart Rate ◽

Sympathetic Nerve Activity ◽

Cardiovascular Regulation ◽

Solitary Tract ◽

Nerve Activity ◽

Renal Sympathetic Nerve Activity ◽

Reflex Bradycardia ◽

Cardiac Slowing ◽

Renal Sympathetic ◽

Stimulation Of

The parasubthalamic nucleus (PSTN) projects extensively to the nucleus of the solitary tract (NTS); however, the function of PSTN in cardiovascular regulation is unknown. Experiments were done in α-chloralose anesthetized, paralyzed, and artificially ventilated rats to investigate the effect of glutamate (10 nl, 0.25 M) activation of PSTN neurons on mean arterial pressure (MAP), heart rate (HR), and renal sympathetic nerve activity (RSNA). Glutamate stimulation of PSTN elicited depressor (−20.4 ± 0.7 mmHg) and bradycardia (−26.0 ± 1.0 beats/min) responses and decreases in RSNA (67 ± 17%). Administration (intravenous) of atropine methyl bromide attenuated the bradycardia response (46%), but had no effect on the MAP response. Subsequent intravenous administration of hexamethonium bromide blocked both the remaining bradycardia and depressor responses. Bilateral microinjection of the synaptic blocker CoCl2 into the caudal NTS region attenuated the PSTN depressor and bradycardia responses by 92% and 94%, respectively. Additionally, prior glutamate activation of neurons in the ipsilateral NTS did not alter the magnitude of the MAP response to stimulation of PSTN, but potentiated HR response by 35%. Finally, PSTN stimulation increased the magnitude of the reflex bradycardia to activation of arterial baroreceptors. These data indicate that activation of neurons in the PSTN elicits a decrease in MAP due to sympathoinhibition and a cardiac slowing that involves both vagal excitation and sympathoinhibition. In addition, these data suggest that the PSTN depressor effects on circulation are mediated in part through activation of NTS neurons involved in baroreflex function.

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Regional Frontal Lobe Response Magnitudes During Affective Shifting Covary With Resting Heart Rate Variability in Healthy Volunteers

Journal of Psychophysiology ◽

10.1027/0269-8803/a000166 ◽

2016 ◽

Vol 30 (4) ◽

pp. 165-174 ◽

Cited By ~ 3

Author(s):

Ryan Smith ◽

John J.B. Allen ◽

Julian F. Thayer ◽

Richard D. Lane

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Healthy Subjects ◽

Emotional Reactivity ◽

Bold Signal ◽

Resting Heart Rate ◽

Functional Magnetic Resonance ◽

Absolute Value ◽

Cardiac Vagal Control ◽

Resting Heart Rate Variability

Abstract. We hypothesized that in healthy subjects differences in resting heart rate variability (rHRV) would be associated with differences in emotional reactivity within the medial visceromotor network (MVN). We also probed whether this MVN-rHRV relationship was diminished in depression. Eleven healthy adults and nine depressed subjects performed the emotional counting stroop task in alternating blocks of emotion and neutral words during functional magnetic resonance imaging (fMRI). The correlation between rHRV outside the scanner and BOLD signal reactivity (absolute value of change between adjacent blocks in the BOLD signal) was examined in specific MVN regions. Significant negative correlations were observed between rHRV and average BOLD shift magnitude (BSM) in several MVN regions in healthy subjects but not depressed subjects. This preliminary report provides novel evidence relating emotional reactivity in MVN regions to rHRV. It also provides preliminary suggestive evidence that depression may involve reduced interaction between the MVN and cardiac vagal control.

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