Sex differences in the relationship between cerebral vascular resistance and sympathetic nerve activity: a magnetic resonance imaging study (680.9)

Abstract

In men, we have found that cerebral vascular resistance (CVR) in the internal carotid (ICA), vertebral (VA) and basilar arteries (BA) is related to muscle sympathetic nerve activity (MSNA). Since sex hormones play a role in blood flow/pressure regulation, we hypothesised that CVR and blood flow in the ICA, VA, and BA would not be related to the level of MSNA or blood pressure (BP) in young women. In normotensive men (n= 11, age; 30 ± 2 yrs) and pre‐menopausal women (n=7; 33±2 yrs) blood flow in the ICA, VA and BA was measured using magnetic resonance phase contrast imaging at 2 locations (1 cm below/above the VA convergence) with concurrent brachial BP measurements. CVR was calculated as mean BP/blood flow. MSNA was similar in men and women (30 ± 1 vs. 28±1 bursts/100 hb) and positively related to CVR in the left and right ICA (r=0.74, r=0.62, P0.05). Interestingly, mean BP was negatively correlated with blood flow in the ICA, VA and BA in men (r=‐0.54, r=‐0.56, r=‐0.50, P<0.05), but not in women (P<0.05). In summary, men with high CVR and low blood flow in the intracranial arteries had higher MSNA and BP. Cerebral blood flow and CVR may be important in setting resting BP and MSNA in men but not in pre‐menopausal women. British Heart Foundation funded.Grant Funding Source: Supported by the British Heart Foundation