Forebrain neural patterns associated with sex differences in autonomic and cardiovascular function during baroreceptor unloading

Kimmerly, Derek S.; Wong, Simon S.; Menon, Ravi S.; Shoemaker, J. Kevin

doi:10.1152/ajpregu.00366.2006

Cited by 46 publications

(56 citation statements)

References 44 publications

(53 reference statements)

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“…In a subsequent study using the postexercise hypotensive state which heightened the degree of sympathetic response to these same lower body negative pressure stimuli the increased heart rate activity further correlated with incremental activity in pathway (b) underlining the involvement of this pathway in the control of the sympathetic cardiac responses to reductions in central blood volume (164). There is some evidence to indicate that there are gender differences in the nature of these responses in that female subjects show a smaller cardiovascular reaction to this experimental paradigm than men and this corresponds with a reduced activation of pathway (b) (163). However (as the authors point out), it was unclear from this study whether the effect was a true centrally originating one, or whether this merely was a reflection of the reduction in baroreceptor afferent input to central regulatory sites.…”

Section: Human Functional Studiesmentioning

confidence: 70%

The Insular Cortex and the Regulation of Cardiac Function

Oppenheimer

Cechetto

2016

Comprehensive Physiology

166

128

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Cortical representation of the heart challenges the orthodox view that cardiac regulation is confined to stereotyped, preprogrammed and rigid responses to exteroceptive or interoceptive environmental stimuli. The insula has been the region most studied in this regard; the results of clinical, experimental, and functional radiological studies show a complex interweave of activity with patterns dynamically varying regarding lateralization and antero-posterior distribution of responsive insular regions. Either acting alone or together with other cortical areas including the anterior cingulate, medial prefrontal, and orbito-frontal cortices as part of a concerted network, the insula can imbue perceptions with autonomic color providing emotional salience, and aiding in learning and behavioral decision choice. In these functions, cardiovascular input and the right anterior insula appear to play an important, if not pivotal role. At a more basic level, the insula gauges cardiovascular responses to exteroceptive and interoceptive stimuli, taking into account memory, cognitive, and reflexive constructs thereby ensuring appropriate survival responses and maintaining emotional and physiological homeostasis. When acquired derangements to the insula occur after stroke, during a seizure or from abnormal central processing of interoceptive or exteroceptive environmental cues as in psychiatric disorders, serious consequences can arise including cardiac electrophysiological, structural and contractile dysfunction and sudden cardiac death.

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Section: Human Functional Studiesmentioning

confidence: 70%

The Insular Cortex and the Regulation of Cardiac Function

Oppenheimer

Cechetto

2016

Comprehensive Physiology

166

128

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“…No sex differences in Cap 50 were found, however. Thus, the susceptibility to hypovolemic circulatory stress caused by LBNP in women does not seem to result from a greater hypovolemic load in women but rather in differences in the autonomic regulation of the cardiovascular system (13,25). Plasma NE is a good marker of the overall sympathetic response and correlates well with muscle sympathetic nerve activity (MSNA) as well as peripheral resistance (7,11,20,23).…”

Section: Discussionmentioning

confidence: 99%

Lower capacitance response and capillary fluid absorption in women to defend central blood volume in response to acute hypovolemic circulatory stress

Lindenberger¹,

Olsen²,

Länne³

2008

American Journal of Physiology-Heart and Circulatory Physiology

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Lindenberger M, Olsen H, Lä nne T. Lower capacitance response and capillary fluid absorption in women to defend central blood volume in response to acute hypovolemic circulatory stress. Am J Physiol Heart Circ Physiol 295: H867-H873, 2008; doi:10.1152/ajpheart.00332.2008.-Acute hemorrhage is a leading cause of death in trauma, and women are more susceptible to hypovolemic circulatory stress than men. The mechanisms underlying the susceptibility are not clear, however. The aim of the present study was to examine the compensatory mechanisms to defend central blood volume during experimental hypovolemia in women and men. Twentytwo women (23.1 Ϯ 0.4 yr) and 16 men (23.2 Ϯ 0.5 yr) were included. A lower body negative pressure (LBNP) of 11-44 mmHg induced experimental hypovolemic circulatory stress. The volumetric technique was used to assess the capacitance response (redistribution of peripheral venous blood to the central circulation) as well as to assess net capillary fluid transfer from tissue to blood in the arm. Plasma norepinephrine (NE) and forearm blood flow were measured before and during hypovolemia, and forearm vascular resistance (FVR) was calculated. LBNP created comparable hypovolemia in women and men. FVR increased less in women during hypovolemic stress, and no association between plasma NE and FVR was seen in women (R 2 ϭ 0.01, not significant), in contrast to men (R 2 ϭ 0.59, P Ͻ 0.05). Women demonstrated a good initial capacitance response, but this was not maintained with time, in contrast to men [e.g., decreased by 24 Ϯ 4% (women) vs. 4 Ϯ 5% (men), LBNP of 44 mmHg, P Ͻ 0.01], and net capillary fluid absorption from tissue to blood was lower in women (0.086 Ϯ 0.007 vs. 0.115 Ϯ 0.011 ml ⅐ 100 ml Ϫ1 ⅐ min Ϫ1 , P Ͻ 0.05). In conclusion, women showed impaired vasoconstriction, reduced capacitance response with time, and reduced capillary fluid absorption during acute hypovolemic circulatory stress, indicating less efficiency to defend central blood volume than men.gender; orthostatic tolerance; baroreceptor sensitivity ACUTE HEMORRHAGE is a leading cause of death in trauma (2, 41). Women are more susceptible to hypovolemic circulatory stress than men (6,13,17,18,48), and clinical studies have found decreased survival in women after penetrating injury as well as burn injuries (19,35). The mechanisms underlying the susceptibility are not entirely clear and are probably multifactorial (17).Lower body negative pressure (LBNP) is an excellent model for acute hemorrhage and hypovolemic circulatory stress, by inducing central hypovolemia and unloading of baroreceptors (8). A decreased baroreceptor sensitivity has been proposed in women by several authors (13,27,42), and women seem to respond with diminished arterial vasoconstriction to the infusion of ␣-receptor agonists (4, 14, 26). Furthermore, a more pronounced decrease in stroke volume and cardiac output has been postulated as the main mechanism for the susceptibility to hypovolemic circulatory stress, due to smaller and functionally stiffer hearts and ...

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“…For example, we identified forebrain regions that demonstrated activation or deactivation responses that matched sex-specific differences in the sympathetic and cardiovascular responses to lower body negative pressure (LBNP; see Ref. 22). The aim of the present investigation was to extend these between-subject observations and determine whether forebrain activity patterns during baroreceptor unloading would match within-subject postexercise differences in the sympathetic and cardiovascular responses to moderate levels of LBNP.…”

mentioning

confidence: 86%

Forebrain regions associated with postexercise differences in autonomic and cardiovascular function during baroreceptor unloading

Kimmerly¹,

Wong²,

Salzer³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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The cortical regions representing peripheral autonomic reactions in humans are poorly understood. This study examined whether changes in forebrain activity were associated with the altered physiological responses to lower body negative pressure (LBNP) following a single bout of dynamic exercise (POST-EX). We hypothesized that, compared with the nonexercised condition (NO-EX), POST-EX would elicit greater reductions in stroke volume (SV) and larger increases in heart rate (HR) and muscle sympathetic nerve activity (MSNA) during LBNP (5, 15, and 35 mmHg). Forebrain neural activity (n = 11) was measured using blood oxygen level-dependent (BOLD) functional magnetic resonance imaging. HR, SV, arterial blood pressure (ABP), and MSNA were collected separately. Compared with NO-EX, baseline ABP was reduced, whereas HR and total vascular conductance (TVC) were elevated in POST-EX (P < 0.05). In both conditions, 5 mmHg LBNP did not elicit a change (from baseline) in any physiological parameter. Compared with NO-EX, 35 mmHg LBNP-mediated decreases in SV and TVC produced greater increases in HR and MSNA during POST-EX (P < 0.05). The right posterior insula and dorsal anterior cingulate cortex demonstrated a larger decrease in BOLD at 5 mmHg LBNP but greater BOLD increase at 15 and 35 mmHg LBNP POST-EX vs. NO-EX (P < 0.005). Conversely, the thalamus and ventral medial prefrontal cortex displayed the opposite BOLD activity pattern (i.e., larger increase at 5 mmHg LBNP but greater decrease at 15 and 35 mmHg LBNP POST-EX vs. NO-EX). Our findings suggest that discrete forebrain regions may be involved with the generation of baroreflex-mediated sympathetic and cardiovascular responses elicited by moderate LBNP.

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Forebrain neural patterns associated with sex differences in autonomic and cardiovascular function during baroreceptor unloading

Cited by 46 publications

References 44 publications

The Insular Cortex and the Regulation of Cardiac Function

The Insular Cortex and the Regulation of Cardiac Function

Lower capacitance response and capillary fluid absorption in women to defend central blood volume in response to acute hypovolemic circulatory stress

Forebrain regions associated with postexercise differences in autonomic and cardiovascular function during baroreceptor unloading

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