Rhythm Of Systolic Blood Pressure Research Articles

Aging disrupts the temporal organization of antioxidant defenses in theheart of male ratsand phase shifts circadian rhythms of systolic blood pressure.

Aging is one of the main risk factors for cardiovascular diseases, and oxidative stress is a key element responsible for the development of age-related pathologies. In addition, the alteration of circadian rhythms also contributes to cardiovascular pathology, but the underlying mechanisms are not well defined. We investigated the aging consequences on the temporal patterns of antioxidant defenses, the molecular clock machinery, and the blood pressure, in the heart of male rats maintained under constant darkness (free running) conditions. Male Holtzman rats from young adult (3-month-old) and older (22-month-old) groups were maintained under constant darkness (12-h dark:12-h dark, DD) condition during fifteen days before the experiment. After the DD period, heart ventricle samples were isolated every 4-h throughout a 24-h period. We observed circadian rhythms of catalase (CAT) and glutathione peroxidase (GPx) mRNA expression, as well as ultradian rhythms of Nrf2 mRNA levels, in the heart of young adult rats. We also found circadian oscillations of CAT and GPx enzymatic activities, reduced glutathione (GSH) and BMAL1 protein in the same group. Interestingly, aging abolished the rhythms of CAT and GPx enzymatic activities, phase-shifted the rhythm's acrophases of GSH and BMAL1 protein levels and turned circadian the ultradian oscillation of Nrf2 expression. Moreover, aging phase-shifted the circadian pattern of systolic blood pressure. In conclusion, aging modifies the temporal organization of antioxidant defenses and blood pressure, probably, as a consequence of a disruption in the circadian rhythm of the clock's transcriptional regulator, BMAL1, in heart.

Prenatal hypoxia increases blood pressure in male rat offspring and affects their response to artificial light at night.

Prenatal hypoxia (PH) has negative consequences on the cardiovascular system in adulthood and can affect the responses to additional insults later in life. We explored the effects of PH imposed during embryonic day 20 (10.5% O2 for 12 h) on circadian rhythms of systolic blood pressure (BP) and heart rate (HR) in mature male rat offspring measured by telemetry. We evaluated: (1) stability of BP and HR changes after PH; (2) circadian variability of BP and HR after 2 and 5 weeks of exposure to artificial light at night (ALAN; 1-2 lx); and (3) response of BP and HR to norepinephrine. PH increased BP in the dark (134 ± 2 mmHg vs. control 127 ± 2 mmHg; p=0.05) and marginally in the light (125 ± 1 mmHg vs. control 120 ± 2 mmHg) phase of the day but not HR. The effect of PH was highly repeatable between 21- and 27-week-old PH male offspring. Two weeks of ALAN decreased the circadian variability of HR (p<0.05) and BP more in control than PH rats. After 5 weeks of ALAN, the circadian variability of HR and BP were damped compared to LD and did not differ between control and PH rats (p<0.05). Responses of BP and HR to norepinephrine did not differ between control and PH rats. Hypoxia at the end of the embryonic period increases BP and affects the functioning of the cardiovascular system in mature male offspring. ALAN in adulthood decreased the circadian variability of cardiovascular parameters, more in control than PH rats.

0349 Circadian Patterns of Blood Pressure Differ Between Retired Night Shift Workers and Retired Day Workers

Abstract Introduction Approximately 15% of full-time employees in the U.S. work outside the traditional daytime schedule. These individuals exhibit circadian rhythm abnormalities and increased rates of cardiovascular disease compared to day shift workers. Altered circadian patterns of cardiovascular function may persist into retirement even after returning to a normal nocturnal sleep schedule, and may contribute to the elevated cardiovascular disease burden among retired night shift workers. The purpose of this study was to determine whether circadian rhythms of cardiovascular indicators differed between retired night shift workers and retired day workers. Methods Participants (N = 72, 53% females, 83% non-Hispanic White, mean age: 68.66 years) were 33 retired night shift workers and 39 retired day workers who completed a 60-hour sleep/circadian laboratory assessment. Blood pressure and heart rate were assessed hourly during a 24-hour constant routine protocol. Multilevel cosinor analysis estimated group differences in circadian rhythms of systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and heart rate (HR). Covariates included age, sex, race, education, and body mass index. Results The 24-hour pattern of DBP (bsine*shiftwork = 1.47, [95% CI: 0.58, 2.35], p = 0.002) and MAP (bsine*shiftwork = 1.38, [95% CI: 0.28, 2.50], p = 0.015) differed between retired night shift workers and retired day workers. Retired night shift workers displayed a later trough of DBP and MAP compared to retired day workers. No group differences were found for circadian rhythms of SBP or HR. Conclusion Retired night shift workers exhibited altered circadian rhythms of blood pressure, which may indicate a circadian “scarring” of night shift work that persists after a return to normal daytime schedule. Future research should investigate explanations for observed differences and the extent to which chronic alterations in cardiovascular circadian rhythms affect morbidity and mortality. Support R01AG047139, T32HL082610, T32HL07560, UL1TR001857

Effects of acupuncture on circadian rhythm of blood pressure in patients with essential hypertension

To observe the effects of acupuncture combined with medication on circadian rhythm of blood pressure in patients with essential hypertension. Sixty-four patients of essential hypertension were randomly divided into an observation group and a control group, 32 cases in each group. All the patients maintained original treatment (taking antihypertensive medication); the patients in the observation group were treated with acupuncture method of "Huoxue Sanfeng, Shugan Jianpi", once a day, five times per week, for totally 6 weeks (30 times). The circadian rhythm of blood pressure and related dynamic parameters were observed before and after treatment in the two groups. (1) The differences of daytime average systolic blood pressure (dASBP), daytime average diastolic blood pressure (dADBP), nighttime average systolic blood pressure (nASBP) and circadian rhythm of systolic blood pressure before and after treatment were significant in the observation group (all P<0.05); the differences of circadian rhythm of blood pressure and related dynamic parameters before and after treatment were insignificant in the control group (all P>0.05). The nASBP and circadian rhythm of systolic blood pressure in the observation group were significantly different from those in the control group (all P<0.05). (2) After the treatment, the spoon-shaped rate of circadian rhythm of blood pressure in the observation group was higher than that in the control group (P<0.05). The acupuncture combined with medication could effectively improve the circadian rhythm of blood pressure and related dynamic parameters in patients with essential hypertension.

TYPES OF INITIAL ORTHOSTATIC REACTIONS DURING ACTIVE ORTHOSTATIC TEST IN PATIENTS WITH ESSENTIAL HYPERTENSION: PP.8.324

Objective: the aim of our study was to investigate the initial orthostatic reactions during active orthostatic test in patients (pts) with essential hypertension (EH). Design and method: 99 EH pts (30 M, 69F), 57,4 ± 1,1 years, grade 1 or 2. During AOT blood pressure (beat to beat) and heart rate measured continuously and non-invasively using the Task Force Monitor. Daily rhythm of systolic blood pressure (BP) was assessed by BP-24 hour monitoring with 20 min day time intervals and 40 min at night time. (BPLab, Russia). The statistical analysis was carried out by nonparametric methods of Mann-Whitney and Fisher exact test with Statistica 6. Results: In all pts average hemodynamic BP (BP-ah) amplitude was 10–30 mm Hg and was registered in the first 15 sec of orthostasis. All pts was divided into the two groups by different types of the BP reaction. In the Group I pts (n = 62) was found short-term decrease BP-ah. This type of BP reaction was more 18,0 ± 8,0 mm Hg after standing with restoration by 15 sec on 75–100% from an initial baseline level. In the Group II pts (n = 37) we found prolonged decrease BP reaction 22 ± 9 mm Hg. - initial orthostatic hypotension. In the Group II compared to group I pts was found higher day DBP (92,0 ± 1,9 vs 87,5 ± 1,5 mm Hg, p < 0,05, respectively), rate of syncope (24/37 vs 13/62, p < 0,001, respectively) and significant abnormal of nocturnal fall of SBP (8,9 ± 1,6 vs 12,4 ± 1,1; p < 0,05, respectively). All groups was not different by left ventricular mass index (169,9 ± 6,1 vs 169,4 ± 5,01; p = 0,5, respectively). Conclusions: In the EH pts with prolonged decrease BP reaction was found significant association high rate syncope and disturbance of circadian BP rhythm.

Daily rhythm of blood pressure at patients with autoimmune thyreoiditis depending on function of the thyroid gland

The purpose of research was to give the comparative characteristic of a daily profile and circadian rhythm of blood pressure at patients with autoimmune thyreoditis depending on function of a thyroid gland. 66 patients with autoimmune thyreoditis and 25 healthy examinees participated in research. The received results testify that the daily rhythm of arterial pressure at patients with autoimmune thyreoditis authentically depends on the functional characteristic of a thyroid gland. Infringements of circadian rhythm of systolic blood pressure «non-dipper» and excessive decrease of diastolic blood pressure at night are characteristic for patients with autoimmune thyreoditis.

Daily Rhythm of Arterial Pressure in Patients with Autoimmune Thyroidite in a Phase Subclinical Hypothyroidism

The purpose of research was studying of a condition circadian rhythms and parameters of a daily structure according to 24-hour monitoring blood pressure at sick with the verified diagnosis of autoimmune thyroidite in a phase of subclinical hypothyroidism. 23 patients (22 women and 1 man) in the age of from 18 till 58 years are surveyed. The control group was made by practically healthy 25 persons without pathology of a thyroid gland and normal values of blood pressure of similar age. It is revealed, that at patients with autoimmune thyroidite in a phase of subclinical hypothyroidism higher levels of systolic blood pressure and diastolic blood pressure in day time and night hours, also infringement circadian a rhythm of systolic blood pressure “non-dipper” at 39,2% of patients are defined. It is received, that according to 24-hour monitoring blood pressure these patients have features of dynamics of the diastolic blood pressure, described increase of diastolic blood pressure in the afternoon and excessive decrease at night in 30,4% of cases.

Diurnal rhythms of blood pressure, heart rate, and locomotor activity in adult and old male Wistar rats

The diurnal rhythms of systolic blood pressure (SBP), diastolic BP (DBP), heart rate (HR), and spontaneous locomotor activity (SLA) were determined in adult (6-month-old) and old (24-month-old) male Wistar rats by using radiotelemetry. The rhythm parameters (mesor, amplitude, acrophase, and percent rhythm) were analyzed by Fast-Fourier Transform and Cosinor methods. We found that the 12-h mean values of SBP, DBP, HR, and SLA were significantly ( p < 0.001) higher in the dark phase than in the light phase in both adult and old rats. The nocturnal 12-h mean value of HR was significantly ( p < 0.01) lower in old than in adult rats. In addition, the differences between diurnal and nocturnal 12-h mean values of SBP and HR were reduced in old rats. There was no significant difference in the 12-h mean values of SBP, DBP, and SLA between old and adult rats. Otherwise, the diurnal HR rhythm amplitude was significantly ( p < 0.01) reduced in old rats (32 ± 2 vs. 46 ± 2 bpm). A nearly 1-h delay in SBP and DBP acrophases (03h55 ± 00h19 vs. 02h57 ± 00h14 and 03h17 ± 00h13 vs. 01h53 ± 00h22, respectively) was found in old rats comparing to adult rats. No significant change in SLA diurnal rhythm was observed in old rats. In conclusion, these results show a decrease in the nocturnal 12-h mean value of HR and an alteration in cardiovascular diurnal rhythms by a 1-h delay of SBP and DBP acrophases and a reduction of HR rhythm amplitude in old Wistar rats.

Effects of photoperiod reduction on rat circadian rhythms of BP, heart rate, and locomotor activity.

The effects of a photoperiod reduction in the entrainment of circadian rhythms of systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and spontaneous locomotor activity (SLA) were determined in conscious Wistar rats by using radiotelemetry. Two groups of seven rats were maintained in a 12:12-h light-dark (12L/12D) photoperiod for 11 wk and then placed in a reduced photoperiod of 8:16-h light-dark (8L/16D) by advancing a 4-h darkness or by advancing and delaying a 2-h darkness for 6 wk. Finally, they were resynchronized to 12L/12D. Advancing a 4-h dark phase induced a 1-h advance of acrophase for SBP, DBP, and HR, but not for SLA. The percent rhythm, amplitude, and the 12-h mean values of all parameters were significantly decreased by the photoperiod reduction. When symmetrically advancing and delaying a 2-h dark phase, a 1 h 20 min delay of acrophases and a decrease in percent rhythms and amplitudes of SBP, DBP, HR, and SLA were observed. Only the 12-h mean values of HR and SLA were decreased. Our findings show that the cardiovascular parameters differ from SLA in phase-shift response to photoperiod reduction and that the adjustment of circadian rhythms to change from 12L/12D to 8L/16D photoperiod depends on the direction of the extension of the dark period.

Acrophase amplitude of ambulatory blood pressure decreases in migraineurs.

Ambulatory blood pressure was recorded and analyzed in 13 migraineurs during headache-free periods and in 11 healthy subjects. Systolic blood pressure, mean blood pressure, diastolic blood pressure, pulse pressure, and pulse rate were recorded for 48 hours (three times every hour from 6 AM to mid-night, once an hour at night). Circadian variation of blood pressure was analyzed using single cosinor analysis and group mean cosinor analysis methods. Single cosinor analysis identified significant circadian rhythm of systolic blood pressure in 10 of 11 control subjects (90.9%) and 5 of 13 migraineurs (38.5%, P < 0.02 versus controls, Fisher's exact test). Incidences of significant circadian rhythm of mean blood pressure and diastolic blood pressure were 100% and 100% in controls, 46.2% and 53.8% in the migraineurs (P < 0.01, P < 0.02 versus controls). Incidences of significant rhythm of pulse pressure were 36.3% in controls and 38.5% in the migraine group (difference was not significant). Group mean cosinor analysis identified significant circadian rhythm in both the migraine group and the controls. The MESOR (midline estimating statistic of rhythm) values of systolic, mean, and diastolic blood pressures showed no significant differences between the migraine group and the controls. Acrophase amplitudes of systolic, mean, and diastolic blood pressure were 4.2, 5.2, and 5.9 mm Hg in the migraine group, respectively; and 7.2, 7.3, and 7.5 mm Hg in the controls, respectively. These amplitudes of systolic, mean, and diastolic blood pressures in the migraine group were significantly smaller than those in the controls. These data suggest that some migraineurs lose or alter their circadian blood pressure rhythm. Evaluating migraineurs as a group, significant circadian rhythm of blood pressure can be identified and oscillation amplitudes of blood pressures are decreased. The present results suggest that migraineurs may be subject to dysfunction of the circadian rhythm generator and the autonomic nervous system. Possible involvement of serotonergic projections from the raphe to the suprachiasmatic nuclei of the hypothalamus in migraine is discussed.

Assessment of age-dependent changes in circadian blood pressure rhythm in patients with essential hypertension.

The effects of age on the circadian blood pressure rhythm of patients with untreated essential hypertension (n = 133, World Health Organization stage I or II) were compared with those of normotensive subjects (n = 91). Subjects were classified into three groups by age: young (less than 40 years old), adult (40-59 years old) and old (greater than or equal to 60 years old). Blood pressure was monitored every 5 min for 24 h, using a finger volume oscillometric device under fixed external conditions. The single cosinor method was used to evaluate circadian rhythm. There was no difference in the amplitude of circadian systolic or diastolic blood pressure rhythm among the different normotensive and essentially hypertensive age groups although a wide distribution of amplitude was noted within each group. The distribution of amplitude was wider in the hypertensive than in the normotensive groups. The amplitude of circadian blood pressure rhythm was independent of the mesor level. On the other hand, the amplitude of circadian heart rate rhythm decreased with increasing age both in normotensive subjects (P less than 0.05, young versus adult or old) and hypertensive patients (P less than 0.01, young and old versus adult). The acrophase of circadian systolic blood pressure rhythm in young hypertensives was greater than that in adult or old hypertensives (P less than 0.05, for both). Such age-dependent changes were not observed in the normotensive groups. Consequently, the acrophase of circadian systolic or diastolic blood pressure rhythm in young hypertensives was larger than that in young normotensives (P less than 0.05, for both systolic and diastolic blood pressure).(ABSTRACT TRUNCATED AT 250 WORDS)