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Intermittent Functioning of Baroreflex Contributes to the Etiology of Hypertension in Spontaneously Hypertensive Rats
Author(s) -
Gu Feng,
Michele Daniel E.,
Carlson Brian E.,
Whitesall Steven,
Fink Gegory D.,
Beard Daniel A
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.04632
Subject(s) - baroreflex , etiology , medicine , cardiology , resistant hypertension , blood pressure , heart rate
The potential roles of the baroreflex in long‐term arterial blood pressure (BP) regulation and in the etiology of primary hypertension have been long debated. We have hypothesized that aging‐associated stiffening of large arteries desensitizes baroreceptors in the aortic arch and carotid sinus, and thereby may contribute to a mechano/neurogenic etiology. To test that hypothesis, we obtained long time‐course continuous arterial pressure data in spontaneously hypertensive (SHR) and control Wistar‐Kyoto (WKY) rats at various ages (7–15 weeks) during the development of the hypertensive phenotype in the SHR animals. Rather than the expected simple proportional relationship between arterial vessel distensibility and baroreflex gain, analysis of data from these animals reveals a markedly intermittent functioning of the baroreflex arc, with long periods (up to several minutes long) with arterial pressure fluctuations coupled to corresponding physiological responses in heart rate and with similarly long periods where the pressure and heart rate fluctuations are not coupled. Several potentially important trends are observed to be associated with the intermittent apparent baroreflex “on” and “off” time periods: (1.) during normal dark‐cycle recording the fraction of time for which the baroreflex is operating in the “on” state ranges from 45–70% for both strains and all ages observed; (2.) the fraction of time in the “on” state decreases with age in both the SHR and WKY strains; (3.) the mean arterial pressure is tightly correlated with fractional “on” time in all rats (see figure ); (4.) mean pressures during “off” states are higher than during “on” states for both strains, both sexes, and at all ages studied; and (5.) mean pressure tends to decrease during “on” states and rise during “off” states in WKY rats, while mean pressure remains elevated at all times in SHR rats. From these observations we hypothesize that impaired function of the baroreflex in the SHR strain contributes to the SHR hypertensive phenotype. This impaired function is reflected in less frequently coupled “on” function in the SHR compared to the WKY and the inability of the functioning baroreflex to reduce pressure during “on” states in the SHR. Support or Funding Information Supported by NIH grant HL139813Correlation between mean arterial pressure and fractional baroreflex “on” time in SHR and WKY rats.