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Sex Differences in Forebrain Modulation of Cardiovascular Function during Lower Body Negative Pressure
Author(s) -
Kimmerly Derek S.,
Wong Savio,
Me Ravi S.,
Shoemaker J. Kevin
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1427
We have previously characterized a cortical network associated with autonomic cardiovascular control during baroreceptor unloading in males. This study examined whether sex‐differences in the activity patterns of this network were associated with differential cardiovascular responses to lower body negative pressure (LBNP, −5 and −35 mmHg). Cortical activity in healthy men (n=8) and women (n=8) was determined using functional magnetic resonance imaging (fMRI). Estimated central venous pressure (CVP), heart rate (HR) and muscle sympathetic nerve activity (MSNA) were collected during a separate test. Random effects analysis (SPM2) was used to identify significant sex‐related cortical activity during steady‐state LBNP (35mmHg versus 5mmHg). Compared with females, males demonstrated a smaller decrease in CVP (4.6 ± 0.4 vs. 5.7 ± 0.3 mmHg) but a greater increase in both HR (9.4 ± 1.4 vs. 4.0 ± 1.0 bpm) and total MSNA (1707 ± 207 vs. 1180 ± 195 a.u.) during 35mmHg LBNP (all, p < 0.05). Significant differences in forebrain acivity (p < 0.001, uncorrected) were observed in the right dorsal posterior insula (RDPI, Male > Female) and the medial prefrontal cortex (MPFC, Female > Male). Results from our previous fMRI study suggested that RDPI and MPFC activity were associated with baroreflex‐mediated sympatho‐excitatory and sympatho‐inhibitory function, respectively. Therefore, differences in the neural activity between these opposing central autonomic sites may contribute to the differential sex‐mediated autonomic responses elicited during baroreceptor unloading. Supported by NSERC, the Canadian Space Agency and the HSFC