Gender differences in vascular responses to carotid baroreflex stimulation (879.14)

Abstract

The relationships between sympathetic nerve activity, arterial blood pressure and cardiac output are strikingly different in young men and women, and further modified by aging. We hypothesised that some of these differences may be mediated by altered baroreflex control of arterial pressure. Full baroreflex response curves are seldom constructed, particularly for vascular resistance responses, and possible gender differences in these responses are unclear.We, therefore, used a variable‐pressure neck collar system to deliver a range of positive and negative pressures to the carotid sinus in young men (n=5) and women (n=5). Beat‐to‐beat mean arterial pressure (MAP), R‐R interval, and brachial blood flow velocity (BBFV) were recorded noninvasively. From these data we constructed full cardiac and forearm vascular resistance (FVR=MAP/BBFV) baroreflex response curves. Gain, set point, threshold and saturation were calculated.Resting heart rates and blood pressures were similar in men and women. Cardiac and FVR baroreflex gains, threshold and saturation were also similar in men and women. The set point for the cardiac responses in women (105±10 mmHg) was greater than in men (77±7 mmHg, p<0.05); the set point for FVR responses was similar. In both groups the latency of the maximal MAP response to negative pressure (13 beats) was larger than positive pressure (7 beats, p<0.05). Overall there was a significant correlation between the set point of the blood pressure response and neck circumference (r= ‐0.64, p<0.05).These data suggest there may be subtle but physiologically relevant differences in carotid baroreflex control in young men and women. Given the impact of gender and age on susceptibility to hypertension, further study is required to evaluate these responses in older men and women.Grant Funding Source: None