Angiotensin II-mediated nondipping during sleep in healthy humans: Effects on baroreflex function at subsequent daytime

Friedhelm Sayk*, Christoph Twesten, Isabel Adametz, Klaas Franzen, Reinhard Vonthein, Christoph Dodt, Moritz Meusel

*Korrespondierende/r Autor/-in für diese Arbeit

Abstract

Blood pressure dipping at night is mediated by sleep-inherent, active downregulation of sympathetic vascular tone. Concomitantly, activity of the renin-angiotensin system is reduced, which might contribute to the beneficial effect of baroreflex downward resetting on daytime blood pressure homeostasis. To evaluate whether experimental nondipping mediated by angiotensin II during sleep would alter blood pressure and baroreflex function the next day in healthy humans, angiotensin-II or placebo (saline) was infused for a 7-h period at night, preventing blood pressure dipping in 11 sleeping normotensive individuals (5 males, balanced, crossover design). Baroreflex function was assessed about 1 h upon awakening and stop of infusion via microneurographic recordings of muscle sympathetic nerve activity (MSNA), showing that resting MSNA was significantly increased following angiotensin II nondipping compared with placebo (P = 0.029), whereas blood pressure and heart rate remained unchanged. Baroreflex sensitivity in response to vasoactive drug challenge was preserved, and neuroendocrine markers of fluid balance and electrolytes did not differ between conditions. Ambulatory blood pressure during subsequent daytime was not altered. Data were compared with analog experiments previously performed within the same subjects during awake daytime (ANCOVA). We conclude that angiotensin-II mediated nocturnal nondipping did not induce blood pressure elevation at subsequent daytime in healthy humans but was linked to increased vasoconstrictive sympathetic activity. This is in contrast to a prolonged increase in blood pressure in corresponding daytime experiments of the same individuals. Evidently, sleep strongly preserves normotensive blood pressure homeostasis in healthy humans. angiotensin II; baroreflex function; nighttime/daytime; nondipping; muscle sympathetic nerve activity.

OriginalspracheEnglisch
ZeitschriftAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Jahrgang318
Ausgabenummer4
Seiten (von - bis)R813-R821
ISSN0363-6119
DOIs
PublikationsstatusVeröffentlicht - 01.04.2020

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  • Forschungsschwerpunkt: Gehirn, Hormone, Verhalten - Center for Brain, Behavior and Metabolism (CBBM)

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