Magnitude of Morning Surge in Blood Pressure Is Associated with Sympathetic but Not Cardiac Baroreflex Sensitivity

Abstract

The ability of the arterial baroreflex to regulate blood pressure may influence the magnitude of the morning surge in blood pressure (MSBP). The aim was to investigate the relationships between sympathetic and cardiac baroreflex sensitivity (BRS) and the morning surge. Twenty-four hour ambulatory blood pressure was recorded in 14 young individuals. The morning surge was defined via the pre-awakening method, which is calculated as the difference between mean blood pressure values 2 h before and 2 h after rising from sleep. The mean systolic morning surge, diastolic morning surge, and morning surge in mean arterial pressures were 15 ± 2, 13 ± 1, and 11 ± 1 mmHg, respectively. During the laboratory protocol, continuous measurements of blood pressure, heart rate, and muscle sympathetic nerve activity (MSNA) were made over a 10-min period of rest. Sympathetic BRS was quantified by plotting MSNA burst incidence against diastolic pressure (sympathetic BRSinc), and by plotting total MSNA against diastolic pressure (sympathetic BRStotal). Cardiac BRS was quantified using the sequence method. The mean values for sympathetic BRSinc, sympathetic BRStotal and cardiac BRS were −1.26 ± 0.26 bursts/100 hb/mmHg, −1.60 ± 0.37 AU/beat/mmHg, and 13.1 ± 1.5 ms/mmHg respectively. Significant relationships were identified between sympathetic BRSinc and the diastolic morning surge (r = 0.62, p = 0.02) and the morning surge in mean arterial pressure (r = 0.57, p = 0.03). Low sympathetic BRS was associated with a larger morning surge in mean arterial and diastolic blood pressure. Trends for relationships were identified between sympathetic BRStotal and the diastolic morning surge (r = 0.52, p = 0.066) and the morning surge in mean arterial pressure (r = 0.48, p = 0.095) but these did not reach significance. There were no significant relationships between cardiac BRS and the morning surge. These findings indicate that the ability of the baroreflex to buffer increases in blood pressure via reflexive changes in MSNA may play a role in determining the magnitude of the MSBP.

Salt intake impacts sympathetic neural control but not morning blood pressure surge in premenopausal women with a history of normal pregnancy

“…We previously demonstrated that MBPS was negatively associated with sympathetic baroreflex sensitivity (BRS) in older hypertensive individuals (41). Johnson et al (25) confirmed our observation in healthy young individuals.…”

Суточный Профиль Артериального Давления У Детей С Хроническим Пиелонефритом И Хронической Болезнью Почек I–III Стадии

“…Although statistically significant between-groups differences in indices of BP morning surge were not obtained by a majority of comparisons, the fact of an increase in magnitude and velocity of BP morning surge in CKD children with reduced renal function deserves attention. It should be noted that the morning BP surge is mediated by rapid sympathetic nervous system activation with the development of vasoconstriction [7,22]. Also, in the morning, the endothelial function decreases, and the level of thrombogenic factors increases [23,24].…”

Automatic detection algorithm for establishing standard to identify “surge blood pressure”

“…The baroreflex is one of the most important physiological reflexes controlling arterial blood pressure [26]. The morning BP surge is one of the phenotypes of the BP variability closely determined by the sympathetic baroreflex [27]. In addition to surge BP, assessing the baroreflex sensitivity by customizing methods based on spontaneous variations [28,29] is also necessary to reveal the mechanism of the variability.…”