Modification of Circadian Blood Pressure and Heart Rate Variability by Five Different Antihypertensive Agents in Spontaneously Hypertensive Rats

Janssen, Ben J. A.; Tyssen, C.M.; Struyker‐Boudier, H. A. J.

doi:10.1097/00005344-199103000-00020

Cited by 55 publications

(44 citation statements)

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“…Further studies with a larger sample size will be required to validate this finding. These findings are in contrast to limited data from the adult rat, which suggest that the SNS mediates the central SCN-driven diurnal rhythm in HR and MAP (17,48). A limitation of the present study is that the effect of the SNS and vagal input were tested separately.…”

Section: Discussioncontrasting

confidence: 74%

The role of the neural sympathetic and parasympathetic systems in diurnal and sleep state-related cardiovascular rhythms in the late-gestation ovine fetus

Jensen

Guild

Booth

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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AJ. The role of the neural sympathetic and parasympathetic systems in diurnal and sleep state-related cardiovascular rhythms in the late-gestation ovine fetus. Am J Physiol Regul Integr Comp Physiol 297: R998 -R1008, 2009. First published July 29, 2009 doi:10.1152/ajpregu.90979.2008.-The efferent mechanisms mediating the well-known diurnal cardiovascular rhythms in the lategestation fetus are only partially understood. In the present study, we evaluated the contribution of the parasympathetic and sympathetic nervous systems (SNS) to these rhythms. Chronically instrumented fetal sheep at a mean (SE) of 122 (1) days gestation (term is 147 days) underwent either chemical sympathectomy with 6-hydroxydopamine the day after surgery (n ϭ 8), vagotomy at surgery (n ϭ 8), or were sham controls (n ϭ 8). Fetal heart rate (HR), fetal HR variability (HRV), mean arterial blood pressure (MAP), carotid blood flow (CaBF), electrocorticogram (ECoG) activity, and nuchal activity were measured continuously for 24 h. Changes between sleep states were determined in a 6-h interval. Control fetal sheep showed consistent diurnal rhythms in fetal HR, HRV, MAP, and CaBF, with maximal activity in the evening, but not in nuchal activity. Sympathectomy was associated with a significant reduction of both fetal HR and HRV, while vagotomy was associated with a fall in fetal HRV (P Ͻ 0.05) but no change in HR. Despite this, most animals in the two intervention groups still showed diurnal rhythms for fetal HR, HRV, MAP, and CaBF, although peak HR may have been delayed in the sympathectomy group (mean 02:22 vs. 23:54 h in controls, P ϭ 0.06). There was no effect of either intervention on sleep state cycling, although state-related cardiovascular rhythms were significantly modulated. These data indicate that, neither the SNS nor vagal activity, in isolation at least, is essential for generating cardiovascular diurnal rhythms in the late-gestation fetus. fetal heart rate variability; diurnal rhythm; fetal sheep; sleep state; autonomic nervous system DESPITE THE COMMON USE OF heart rate (HR) and HR variability (HRV) for fetal surveillance, the underlying efferent mechanisms controlling these rhythms remain incompletely understood (29). Diurnal rhythms in fetal HR and HRV are well established in late gestation in the fetal human (44), nonhuman primates (39), and sheep (3,4,9,11,42). These circadian rhythms are thought to be entrained by maternal signals (28) and coordinated, in part, by signals from a fetal "biological clock" in the suprachiasmatic nucleus (SCN) (5,26,41), although other fetal tissues may be involved (37). A study in infants and children showed a circadian rhythm in HR and HRV and confirmed progressive maturation of the autonomic nervous system with age, suggesting the hypothesis that the sympathetic withdrawal associated with mature, organized sleep is largely responsible for those rhythms (24).The SCN neurons communicate with the superior cervical ganglion, whose sympathetic terminals then release norepinephrine in end organs in a...

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Section: Discussioncontrasting

confidence: 74%

The role of the neural sympathetic and parasympathetic systems in diurnal and sleep state-related cardiovascular rhythms in the late-gestation ovine fetus

Jensen

Guild

Booth

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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“…However, this seems unlikely in view of the similar sociocultural background of patients and control subjects as well as the mild to moderate degree of renal failure that uncommonly interferes with physical activity. Also, a variety of evidence from adults with pacemakers or biventricular assist devices, pregnant women, and spontaneously hypertensive rats suggests that regulation of BP and HR rhythmicity involves separate physiologic mechanisms (31)(32)(33)(34). For example, early pharmacologic experiments by Parati at al.…”

Section: Discussionmentioning

confidence: 99%

Ultradian but not Circadian Blood Pressure Rhythms Correlate with Renal Dysfunction in Children with Chronic Renal Failure

Wühl

Hadtstein

Mehls

et al. 2005

Journal of the American Society of Nephrology

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Whereas the diurnal fall of BP (dipping) is an important prognostic marker in patients with chronic renal failure (CRF), the integrity of physiologic ultradian (i.e., shorter than 24 h) cardiovascular rhythms in patients with CRF is unknown. Also, the relationship between conventional dipping analysis and Fourier spectral rhythm analysis has not been examined in renal hypertension. The prevalence and dimensions of the circadian and three ultradian (12, 8, and 6 h) cardiovascular rhythms were studied by ambulatory BP monitoring in 214 children (aged 3 to 18 yr) with CRF (stage 2 to 4 chronic kidney disease) and no antihypertensive treatment compared with 938 healthy control subjects, and the relationship of rhythm characteristics to conventional dipping parameters, renal function, proteinuria, and serum electrolytes was assessed. The CRF cohort exhibited significantly reduced amplitudes of the circadian and all ultradian cardiovascular rhythms studied (all P < 0.01). Moreover, all BP and most heart rate rhythms showed significantly delayed acrophases (time of peak; P < 0.01). Whereas conventional BP dipping parameters (day/night difference, day/night ratio) and the 24-h BP amplitude were independent of renal function, the 8-h BP amplitude was positively correlated with GFR (r ‫؍‬ 0.3, P ‫؍‬ 0.01) and inversely correlated with the urinary protein/creatinine ratio (r ‫؍‬ ؊0.27, P < 0.05), and the 6-h BP amplitude was inversely correlated with proteinuria (r ‫؍‬ ؊0.3, P < 0.02). Children who displayed 24-or 12-h cardiovascular rhythms had significantly lower serum calcium levels than children without these rhythms. In summary, children with CRF display not only blunted circadian but also blunted ultradian cardiovascular rhythms. Ultradian but not circadian rhythms or conventional dipping parameters are quantitatively associated with renal function and proteinuria.

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“…In most cases, data on hormonal reflex responses are not reported, 10,[13][14][15][16][20][21][22] while the heart rate (HR) response has been reported as either increased 20 or unchanged. 21,22,15,16 Use of hydralazine as antihypertensive therapy in an obesity-hypertension model is further complicated by the fact that potential side effects are similar to physiological changes often seen in obesity (e.g., tachycardia and activation of the reninangiotensin system (RAS)). 9,23,24 Therefore, the purposes of this study were two-fold.…”

Section: Introductionmentioning

confidence: 99%

Hydralazine as antihypertensive therapy in obesity-related hypertension

2004

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OBJECTIVE:The objectives were two-fold: (1) determine whether the use of hydralazine as antihypertensive therapy during obesity development exacerbated obesity-related cardioacceleration and hormonal abnormalities; (2) determine whether the absence of hypertension in obesity attenuated obesity-related abnormalities in hemodynamics, cardiac hypertrophy, and hormonal profile. DESIGN: Female New Zealand White rabbits were divided into lean control (n ¼ 12), lean hydralazine-treated (n ¼ 9), obese control (n ¼ 11), and obese hydralazine-treated (n ¼ 8) groups. Pretreatment mean blood pressure (BP) and heart rate (HR) were determined using telemetry. Pretreatment BP was maintained during 12 weeks of obesity development using hydralazine. MEASUREMENTS: Chronically measured BP and HR; plasma/blood volume; wet and dry ventricular weights; body fat/water; and hormonal profile (plasma renin activity, aldosterone, cortisol, atrial natriuretic peptide, adrenaline, and noradrenaline). RESULTS: Hydralazine treatment in obese animals attenuated obesity-related renin-angiotensin system (RAS) activation. In contrast, RAS was activated in lean hydralazine, as indicated by increased plasma aldosterone. The absence of hypertension in obese hydralazine did not result in attenuation of cardioacceleration, cardiac hypertrophy, or intravascular volumes. CONCLUSIONS: Hydralazine treatment in obese rabbits did not exacerbate obesity-related cardiovascular and hormonal alterations. Cardioacceleration and cardiac hypertrophy persisted in obese hydralazine despite BP control, suggesting hypertension-independent effects of obesity on these variables. Hydralazine's effects on RAS activation differed in lean and obese rabbits, suggesting that the systemic effects of hydralazine as a control therapy in evaluation of antihypertensive medications may differ depending on the underlying pathology.

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Modification of Circadian Blood Pressure and Heart Rate Variability by Five Different Antihypertensive Agents in Spontaneously Hypertensive Rats

Cited by 55 publications

References 0 publications

The role of the neural sympathetic and parasympathetic systems in diurnal and sleep state-related cardiovascular rhythms in the late-gestation ovine fetus

The role of the neural sympathetic and parasympathetic systems in diurnal and sleep state-related cardiovascular rhythms in the late-gestation ovine fetus

Ultradian but not Circadian Blood Pressure Rhythms Correlate with Renal Dysfunction in Children with Chronic Renal Failure

Hydralazine as antihypertensive therapy in obesity-related hypertension

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