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Central correlation of muscle sympathetic nerve activation during baroreflex unloading – a microneurography–positron emission tomography study
Author(s) -
Krämer Heidrun H.,
Ament StephanJohann,
Breimhorst Markus,
Klega Andre,
Schmieg Katharina,
Endres Corina,
Buchholz HansGeorg,
Elam Mikael,
Schreckenberger Mathias,
Birklein Frank
Publication year - 2014
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.12437
Subject(s) - microneurography , baroreflex , positron emission tomography , medicine , anatomy , nuclear medicine , heart rate , blood pressure
The baroreceptor reflex controls spontaneous fluctuations in blood pressure. One major control variable of the baroreflex is the sympathetic vasoconstrictor activity to muscles [ MSNA ; burst frequency ( BF ) and burst incidence ( BI )], which can be quantitatively assessed by microneurography. We aimed to investigate the central regions involved in baroreflex regulation of MSNA . Healthy men (mean age 25 years) participated in three experimental sessions. (i) Microneurography recordings of MSNA from the left peroneal nerve during rest and baroreflex unloading, induced by lower body negative pressure ( LBNP ; −40 mmHg). If MSNA could be reliably recorded throughout this procedure ( n = 15), the subjects entered the positron emission tomography ( PET ) experiments. The two PET sessions took place in a randomised order. Cerebral glucose metabolism (18‐fluorodeoxyglucose) was analysed after: (ii) baroreflex unloading (LBNP); and (iii) control condition (lying in the LBNP chamber without suction). The PET data were analysed employing SPM 8. LBNP elicited a significant increase in MSNA in all successfully recorded subjects ( BI : P = 0.001; F = 5.54; BF: P < 0.001; F = 36.59). As compared with the control condition, LBNP was associated with increased PET regional glucose metabolism bilaterally in the orbitofrontal cortex ( OFC ; BA 11, 47). Related to the rise of BF , there was increased activation of the left OFC ( BA 11); related to the rise of BI there was increased activation of the brainstem corresponding to the rostral ventrolateral medulla. Our data support a role for the ventrolateral medulla and the OFC in baroreflex‐mediated control of MSNA in humans.