Age and gender dependency of baroreflex sensitivity in healthy subjects

Abstract

We evaluated the correlates of baroreflex sensitivity (BRS) in healthy subjects. The study consisted of 117 healthy, normal-weight, nonsmoking male and female subjects aged 23-77 yr. Baroreflex control of heart rate was measured by using the phenylephrine bolus-injection technique. Frequency- and time-domain analysis of heart rate variability and an exercise test were performed. Plasma norepinephrine, epinephrine, insulin, and arginine vasopressin concentrations and plasma renin activity were measured. In the univariate analysis, BRS correlated with age (r = -0.65, P < 0.001), diastolic blood pressure (r = -0.47, P < 0.001), exercise capacity (r = 0.60, P < 0.001), and the high-frequency component of heart rate variability (r = 0.64, P < 0.001). There was also a significant correlation between BRS and plasma norepinephrine concentration (r = -0.22, P < 0.05) and plasma renin activity (r = 0.32, P < 0.001). According to the multivariate analysis, age and gender were the most important physiological correlates of BRS. They accounted for 52% of interindividual BRS variation. In addition, diastolic blood pressure and high-frequency component of heart rate variability were significant independent correlates of BRS. BRS was significantly higher in men than in women (15.0 +/- 1.2 vs. 10.2 +/- 1.1 ms/mmHg, respectively; P < 0.01). Twenty-four percent of women > 40 yr old and 18% of men > 60 yr old had markedly depressed BRS (< 3 ms/mmHg). We conclude that physiological factors, particularly age and gender, have significant impact on BRS in healthy subjects. In addition, we demonstrate that BRS values that have been proposed to be useful in identifying postinfarction patients at high risk of sudden death are frequently found in healthy subjects.

Women Have Lower Tonic Autonomic Support of Arterial Blood Pressure and Less Effective Baroreflex Buffering Than Men

“…10 Indeed, the gender-related difference in BRB in the present study was almost as great as the difference recently found between healthy adults and patients with long-standing essential hypertension. 10,16 Thus, consistent with previous reports of gender-related differences in other ANS-cardiovascular functions, [1][2][3][4]8,[23][24][25] the present findings indicate that subject gender is a major source of interindividual variability in tonic ANS support of BP and BRB of BP in healthy adult humans.…”

Reflex Cardiac Activity in Ischemia and Reperfusion

“…In accordance with previous findings in patients with chronic MI 17 and in healthy subjects, 18 we found only weak correlations of norepinephrine concentrations with baroreflex response. In the present study, norepinephrine concentrations were significantly higher in patients with incomplete reperfusion, reflecting a higher background efferent sympathetic activation.…”

Arterial blood pressure response to head-up tilt test and orthostatic tolerance in nurses

“…The majority of studies have shown that BRS is reduced during HUT [41][42][43], while a few studies have reported that it is augmented [30]. Thus, BRS changes in this study were virtually consistent with the former results.…”

“…Given that BRS decreases as age increases [43], and thus is a confounding factor, we examined the correlation of age with BRS using regression analysis. We found no significant correlation in either group between age and BRS.…”