Gender-related differences in the baroreceptor reflex control of heart rate in normotensive humans

Abstract

The present study investigates the baroreceptor reflex control of heart rate (HR) of normotensive male and female human volunteers under two conditions: bolus- and infusion-evoked elevations of blood pressure by intravenous administration of phenylephrine. Average age and blood pressure were similar in both sexes, but females had a significantly lower heart period (HP; higher HR). A major difference existed between the two sexes when the blood pressure was elevated by the bolus method. Females had a significantly (50%) smaller baroreflex sensitivity (regression coefficient), which inferred a gender-related difference in baroreceptor reflex control of HR. However, because a positive correlation existed between basal HP and baroreflex sensitivity, it was important to investigate whether this difference was related to the significantly lower basal HP in females. This possibility was ruled out because a similar difference still existed when the data were collected from another group of females who had basal HP values similar to those of males. This gender-related difference in baroreceptor reflex control of HR seems to depend on the pattern by which the pressor stimulus is evoked. The baroreceptor HP response to a slowly developing pressor response that was maintained at a steady-state level was very similar in both sexes. Because the HP response to abrupt (bolus-evoked) pressor stimuli mainly reflects the activity of the vagal component, our findings suggest that the cardiac vagal component seems to play a substantially smaller role in the baroreflex-mediated bradycardia in females.

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.…”

Alcohol and arrhythmias: a comprehensive review

“…Animal and normal human volunteer studies have confirmed similar acute, as well as chronic, effects of alcohol on baroreceptor responsiveness (40,41).. Gender-related differences in baroreceptor reflex control mechanisms have been demonstrated which might explain different dose response relationships between alcohol and arrhythmias in males and females (42).…”

Maturation of Cardiovagal Autonomic Function From Childhood to Young Adult Age

“…When male and female subjects 20 to 80 years old were studied by use of dynamic pressure elevations with the phenylephrine bolus method, BRSs of males were found to be higher than those of females. 42,43 However, when the pressor response developed slowly with the infusion method, the heart rate response was similar in both sexes. 42 Because the heart rate response to abrupt pressure stimuli reflects primarily the activity of the vagal component, vagal activation seems to play a smaller role in the baroreflex-mediated bradycardia in females.…”

“…42,43 However, when the pressor response developed slowly with the infusion method, the heart rate response was similar in both sexes. 42 Because the heart rate response to abrupt pressure stimuli reflects primarily the activity of the vagal component, vagal activation seems to play a smaller role in the baroreflex-mediated bradycardia in females. We, in the present study, and other investigators earlier, could not demonstrate sex-related differences in spontaneous indices, which might be explained by the slowly developing nature of spontaneous fluctuations in arterial pressure.…”