Therapeutic effects of evening administration of guanabenz and clonidine on morning hypertension: evaluation using home-based blood pressure measurements

Morning blood pressure surge: pathophysiology, clinical relevance and therapeutic aspects

Morning hours are the period of the day characterized by the highest incidence of major cardiovascular events including myocardial infarction, sudden death or stroke. They are also characterized by important neurohormonal changes, in particular, the activation of sympathetic nervous system which usually leads to a rapid increase in blood pressure (BP), known as morning blood pressure surge (MBPS). It was hypothesized that excessive MBPS may be causally involved in the pathogenesis of cardiovascular events occurring in the morning by inducing hemodynamic stress. A number of studies support an independent relationship of MBPS with organ damage, cerebrovascular complications and mortality, although some heterogeneity exists in the available evidence. This may be due to ethnic differences, methodological issues and the confounding relationship of MBPS with other features of 24-hour BP profile, such as nocturnal dipping or BP variability. Several studies are also available dealing with treatment effects on MBPS and indicating the importance of long-acting antihypertensive drugs in this regard. This paper provides an overview of pathophysiologic, methodological, prognostic and therapeutic aspects related to MBPS.

Morning surge in blood pressure and sympathetic activity in Mongolians and Han Chinese: a multimodality investigation of hypertension and dyssomnia

Background

Hypertension and dyssomnia are increasing significantly in Mongolians, and the related factors of ethnic differences in hypertension and dyssomnia between Mongolians and Han Chinese are unclear. This study examined the relationship of morning surge in blood pressure (MBP) with ethnicity, sleep situation, and sympathetic activity throughout the day.

Methods

Of 692 hypertensive patients screened, 202 subjects with dyssomnia were selected. They were then divided into Mongolian (n = 87) and Han (n = 115) groups. The differences in dyssomnia, 24-h blood pressure, and urinary catecholamine were analyzed in all subjects; they were then further divided according to the degree of dyssomnia (low, moderate, and severe) to determine the differences in blood pressure and catecholamine.

Results

Mongolians had a lower history of smoking, daytime dysfunction, nocturnal heart rates, and dopamine levels, but their body mass index, triglyceride, fasting glucose, morning surge in systolic blood pressure (MSBP), nocturnal systolic blood pressure (NSBP), nocturnal diastolic blood pressure, daytime systolic blood pressure, daytime heart rates, and dopamine level (D-DA) were higher than those of Han Chinese. With the aggravation of dyssomnia, MSBP, NSBP, D-NE, daytime epinephrine, and D-DA of Mongolians and Han Chinese increased gradually, but the rate of increase was faster in the latter (p < 0.05). D-DA was entered into the MSBP regression model of Mongolians (intercept, 157 mmHg), whereas D-DA and D-NE were entered into the MSBP regression model of Han Chinese (intercept, 142 mmHg).

Conclusion

Worsened dyssomnia induces higher MSBP and augments sympathetic excitability in Mongolians and Han Chinese. Mongolians with hypertension and dyssomnia had higher MSBP baseline and D-DA but lower N-DA. With an increase in D-DA, MSBP in Han and Mongolian patients increased gradually.

The Effects of Rilmenidine and Perindopril on Arousal Blood Pressure during 24 Hour Recordings in SHR

The surge in arterial pressure during arousal in the waking period is thought to be largely due to activation of the sympathetic nervous system. In this study we compared in SHR the effects of chronic administration of the centrally acting sympatholytic agent rilmenidine with an angiotensin converting enzyme inhibitor perindopril on the rate of rise and power of the surge in mean arterial pressure (MAP) that occurs with arousal associated with the onset of night. Recordings were made using radiotelemetry in 17 adult SHR before and after treatment with rilmenidine (2mg/kg/day), perindopril (1mg/kg/day) or vehicle in the drinking water for 2 weeks. Rilmenidine reduced MAP by 7.2 ± 1.7mmHg while perindopril reduced MAP by 19 ± 3mmHg. Double logistic curve fit analysis showed that the rate and power of increase in systolic pressure during the transition from light to dark was reduced by 50% and 65%, respectively, but had no effect on diastolic pressure. Rilmenidine also reduced blood pressure variability in the autonomic frequency in the active period as assessed by spectral analysis which is consistent with reduction in sympathetic nervous system activity. Perindopril had no effect on the rate or power of the arousal surge in either systolic or diastolic pressure. These results suggest that the arousal induced surge in blood pressure can largely be reduced by an antihypertensive agent that inhibits the sympathetic nervous system and that angiotensin converting enzyme inhibition, while effective in reducing blood pressure, does not alter the rate or power of the surge associated with arousal.

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

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 BRS_inc), and by plotting total MSNA against diastolic pressure (sympathetic BRS_total). Cardiac BRS was quantified using the sequence method. The mean values for sympathetic BRS_inc, sympathetic BRS_total 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 BRS_inc 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 BRS_total 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.

Direct Vasodilators and Sympatholytic Agents

Direct vasodilators and sympatholytic agents were some of the first antihypertensive medications discovered and utilized in the past century. However, side effect profiles and the advent of newer antihypertensive drug classes have reduced the use of these agents in recent decades. Outcome data and large randomized trials supporting the efficacy of these medications are limited; however, in general the blood pressure-lowering effect of these agents has repeatedly been shown to be comparable to other more contemporary drug classes. Nevertheless, a landmark hypertension trial found a negative outcome with a doxazosin-based regimen compared to a chlorthalidone-based regimen, leading to the removal of α-1 adrenergic receptor blockers as first-line monotherapy from the hypertension guidelines. In contemporary practice, direct vasodilators and sympatholytic agents, particularly hydralazine and clonidine, are often utilized in refractory hypertension. Hydralazine and minoxidil may also be useful alternatives for patients with renal dysfunction, and both hydralazine and methyldopa are considered first line for the treatment of hypertension in pregnancy. Hydralazine has also found widespread use for the treatment of systolic heart failure in combination with isosorbide dinitrate (ISDN). The data to support use of this combination in African Americans with heart failure are particularly robust. Hydralazine with ISDN may also serve as an alternative for patients with an intolerance to angiotensin antagonists. Given these niche indications, vasodilators and sympatholytics are still useful in clinical practice; therefore, it is prudent to understand the existing data regarding efficacy and the safe use of these medications.

Morning surge in blood pressure is associated with reactivity of the sympathetic nervous system

BACKGROUND

An exaggerated morning surge in blood pressure (BP) closely relates to target organ damage and cardiovascular risk, but whether the causative mechanism involves greater reactivity of the sympathetic nervous system (SNS) is unknown. We determined whether the response of the SNS to a cold pressor test predicted the BP morning surge.

METHODS

Ambulatory BP recordings were obtained from 14 men and 19 women (age = 41±4 years), and the amplitude (day-night difference), rate of rise (RoR), rate by amplitude product (BPPower), and morning BP surge (MBPS; post-awake minus pre-awake) of morning mean arterial pressure (MAP) were determined. The reactivity of the SNS to CPT was assessed by recording of muscle sympathetic nerve activity (MSNA).

RESULTS

CPT induced a marked increase in MAP and all parameters of MSNA, including burst amplitude. Log-normalized BPPower positively correlated with the overall average CPT-induced increases in total MSNA (r = 0.38; P = 0.04) and burst amplitude (r = 0.43; P = 0.02) but was not related to the increase in MSNA frequency. Furthermore, a strong positive linear trend in the CPT-induced changes in burst amplitude across tertiles of BPPower and RoR was observed. BPPower and RoR were not related to CPT-induced hemodynamic changes. The MBPS did not correlate with any of the CPT-induced changes in vascular or MSNA variables.

CONCLUSIONS

These results suggest that the central nervous system mechanisms influencing the increase in MSNA burst amplitude during arousal may also be fundamental in determining the rate and power of BP rise during the morning period.

G protein-coupled receptors revisited: therapeutic applications inspired by synthetic biology

G protein-coupled receptors (GPCRs) mediate the majority of cellular responses to hormones and neurotransmitters within the human body. They have much potential in the emerging field of synthetic biology, which is the rational, systematic design of biological systems with desired functionality. The responsiveness of GPCRs to a plethora of endogenous and exogenous ligands and stimuli make them ideal sensory receptor modules of synthetic gene networks. Such networks can activate target gene expression in response to a specific stimulus. Additionally, because GPCRs are important pharmacological targets of various human diseases, genes encoding their protein/peptide ligands can also be incorporated as target genes of the response output elements of synthetic gene networks. This review aims to critically examine the potential role of GPCRs in constructing therapeutic synthetic gene networks and to discuss various challenges in utilizing GPCRs for synthetic biology applications.

Pharmaceutically controlled designer circuit for the treatment of the metabolic syndrome

Synthetic biology has significantly advanced the design of genetic devices that can reprogram cellular activities and provide novel treatment strategies for future gene- and cell-based therapies. However, many metabolic disorders are functionally linked while developing distinct diseases that are difficult to treat using a classic one-drug-one-disease intervention scheme. For example, hypertension, hyperglycemia, obesity, and dyslipidemia are interdependent pathologies that are collectively known as the metabolic syndrome, the prime epidemic of the 21st century. We have designed a unique therapeutic strategy in which the clinically licensed antihypertensive drug guanabenz (Wytensin) activates a synthetic signal cascade that stimulates the secretion of metabolically active peptides GLP-1 and leptin. Therefore, the signal transduction of a chimeric trace-amine-associated receptor 1 (cTAAR1) was functionally rewired via cAMP and cAMP-dependent phosphokinase A (PKA)-mediated activation of the cAMP-response element binding protein (CREB1) to transcription of synthetic promoters containing CREB1-specific cAMP response elements. Based on this designer signaling cascade, it was possible to use guanabenz to dose-dependently control expression of GLP-1-Fc(mIgG)-Leptin, a bifunctional therapeutic peptide hormone that combines the glucagon-like peptide 1 (GLP-1) and leptin via an IgG-Fc linker. In mice developing symptoms of the metabolic syndrome, this three-in-one treatment strategy was able to simultaneously attenuate hypertension and hyperglycemia as well as obesity and dyslipidemia. Using a clinically licensed drug to coordinate expression of therapeutic transgenes combines drug- and gene-based therapies for coordinated treatment of functionally related metabolic disorders.

[Dexmedetomidine and clonidine: a review of their pharmacodynamy to define their role for sedation in intensive care patients]

Alpha-2 adrenergic agonists ("alpha-2 agonists") present multiple pharmacodynamic effects: rousable sedation, decreased incidence of delirium in the setting of critical care, preservation of respiratory drive, decreased whole body oxygen consumption, decreased systemic and pulmonary arterial impedance, improved left ventricular systolic and diastolic function, preserved vascular reactivity to exogenous catecholamines, preserved vasomotor baroreflex with lowered set point, preserved kidney function, decreased protein catabolism. These pharmacodynamic effects explain the interest for these drugs in the critical care setting. However, their exact role for sedation in critically ill-patients remains open for further studies. Given the few double-blind randomized multicentric trials available, the present non exhaustive analysis of the literature aims at presenting the utilization of alpha-2 agonists as potential first-line sedative agents, in the critical care setting. Suggestions regarding the use of alpha-2 agonists as sedatives are detailed.

Comparison of effects of angiotensin II receptor blocker on morning home blood pressure and cardiorenal protection between morning administration and evening administration in hypertensive patients: the COMPATIBLE study

Whether the time of administering the angiotensin receptor antagonist olmesartan influences antihypertensive and renoprotective effectiveness remains unclear. This study compared the effects of olmesartan on morning home blood pressure (MHBP), office BP (OBP) and renoprotective parameters between morning and evening administration. A total of 218 patients with primary hypertension were randomly assigned to receive olmesartan once daily in the morning (morning-dose group) or evening (evening-dose group), and 188 completed the study protocol (morning-dose group, n=95; evening-dose group, n=93). In both groups, morning home systolic BP, morning home diastolic BP, office systolic BP and office diastolic BP decreased significantly. There was no significant difference between the groups in MHBP or OBP after 6 months of treatment. The urinary albumin-to-creatinine ratio (UACR) decreased from 13.9 to 6.9 mg g(-1) (geometric means, P<0.001) in the morning-dose group and from 14.4 to 9.1 mg g(-1) (P<0.001) in the evening-dose group. The changes in UACR after treatment did not differ significantly between the groups. SV1+RV5 decreased significantly from baseline to 6 months in the morning-dose group (P<0.001) and the evening-dose group (P<0.01), and did not differ significantly between the groups. In conclusion, olmesartan effectively decreased MHBP, OBP, SV1+RV5 and UACR regardless of whether the drug was administered in the morning or in the evening. Our results suggest that olmesartan can be prescribed once daily, either in the morning or in the evening.

Genes influencing circadian differences in blood pressure in hypertensive mice

Essential hypertension is a common multifactorial heritable condition in which increased sympathetic outflow from the central nervous system is involved in the elevation in blood pressure (BP), as well as the exaggerated morning surge in BP that is a risk factor for myocardial infarction and stroke in hypertensive patients. The Schlager BPH/2J mouse is a genetic model of hypertension in which increased sympathetic outflow from the hypothalamus has an important etiological role in the elevation of BP. Schlager hypertensive mice exhibit a large variation in BP between the active and inactive periods of the day, and also show a morning surge in BP. To investigate the genes responsible for the circadian variation in BP in hypertension, hypothalamic tissue was collected from BPH/2J and normotensive BPN/3J mice at the ‘peak’ (n = 12) and ‘trough’ (n = 6) of diurnal BP. Using Affymetrix GeneChip® Mouse Gene 1.0 ST Arrays, validation by quantitative real-time PCR and a statistical method that adjusted for clock genes, we identified 212 hypothalamic genes whose expression differed between ‘peak’ and ‘trough’ BP in the hypertensive strain. These included genes with known roles in BP regulation, such as vasopressin, oxytocin and thyrotropin releasing hormone, as well as genes not recognized previously as regulators of BP, including chemokine (C-C motif) ligand 19, hypocretin and zinc finger and BTB domain containing 16. Gene ontology analysis showed an enrichment of terms for inflammatory response, mitochondrial proton-transporting ATP synthase complex, structural constituent of ribosome, amongst others. In conclusion, we have identified genes whose expression differs between the peak and trough of 24-hour circadian BP in BPH/2J mice, pointing to mechanisms responsible for diurnal variation in BP. The findings may assist in the elucidation of the mechanism for the morning surge in BP in essential hypertension.

Cardiovascular responses to aversive and nonaversive stressors in Schlager genetically hypertensive mice

BACKGROUND

Schlager inbred hypertensive mice (BPH/2J) have been suggested to have high blood pressure (BP) due to an overactive sympathetic nervous system (SNS). The brain nuclei associated with the hypertension are also those involved in the integration of the cardiovascular responses to stress. Therefore, in the present study, we hypothesize that an increased contribution of the SNS in BPH/2J mice may culminate in a greater pressor response to stressful stimuli in these hypertensive mice than normotensive (BPN/3J) mice.

METHODS

Male hypertensive BPH/2J and normotensive BPN/3J mice were implanted with telemetry devices and exposed to a series of behavioral "stress" tests including aversive stress (shaker, clean cage switch, and restraint) and nonaversive stress (feeding).

RESULTS

Aversive stress caused a 67-88% greater pressor response in BPH/2J compared with BPN/3J mice. By contrast, the feeding-induced pressor response was not different between groups. All stressors induced tachycardia that was less in BPH/2J mice (feeding and restraint) and others were not different between groups (clean cage switch and shaker).

CONCLUSIONS

These findings indicate that hypertension in BPH/2J mice is associated with greater pressor responsiveness to aversive stress but not to appetitive arousal. Thus, BPH/2J hypertensive mice may be a particularly relevant model for human hypertensive patients that overrespond to daily stressors.

Role of the sympathetic nervous system in Schlager genetically hypertensive mice

Early studies indicate that the hypertension observed in the Schlager inbred mouse strain may be attributed to a neurogenic mechanism. In this study, we examined the contribution of the sympathetic nervous system in maintaining hypertension in the BPH/2J mouse and used c-Fos immunohistochemistry to elucidate whether neuronal activation in specific brain regions was associated with waking blood pressure. Male hypertensive (BPH/2J; n=14), normotensive (BPN/3J; n=18), and C57/Bl6 (n=5) mice were implanted with telemetry devices, and after 10 days of recovery, recordings of blood pressure, heart rate, and locomotor activity were measured to determine circadian variation. Mean arterial pressure was higher in BPH/2J than in BPN/3J or C57/Bl6 mice (P<0.001), and BPH/2J animals showed exaggerated day-night differences (17+/-2 versus 6+/-1 mm Hg in BPN/3J or +8+/-2 mm Hg in C57/Bl6 mice; P<0.001). Acute sympathetic blockade with pentolinium (7.5 mg/kg IP) during the active and inactive phases reduced blood pressure to comparable levels in BPH/2J and BPN/3J mice. The number of c-Fos-labeled cells was greater in the amygdala (+180%; P<0.01), paraventricular nucleus (+110%; P<0.001), and dorsomedial hypothalamus (+48%; P<0.001) in the active (hypertensive) phase in BPH/2J compared with BPN/3J mice. The level of neuronal activation was mostly similar in these regions in the inactive phase. Of all of the regions studied, neuronal activation in the medial amygdala, as detected by c-Fos, was highly correlated to mean arterial pressure (r=0.98). These findings indicate that the hypertension is largely attributable to sympathetic nervous system activity, possibly generated through greater levels of arousal regulated by neurons located in the medial amygdala.

Early Morning Blood Pressure Surge

Alterations in the circadian rhythm of blood pressure, whether a loss of the nighttime dip or an exaggeration of the early morning increase that occurs upon rising, indicate increased cardiovascular risk. Estimates of the magnitude of the blood pressure surge on rising vary depending on technique and population, but it is usually around 10-30 mm Hg systolic and 7-23 mm Hg diastolic. The magnitude of the surge increases with age, alcohol consumption, and smoking and is greater in whites. Blood pressure variations and morning plasma aldosterone are closely correlated. A high morning surge is linked to increased target organ damage as well as strokes and other cardiovascular complications. Therapeutic options exist to reduce the magnitude of the morning blood pressure surge-notably, the use of drugs with a long duration of action, the use of medications that specifically antagonize the morning surge (such as alpha blockers), and the administration of drugs upon awakening but before rising.

Prognostic Significance for Stroke of a Morning Pressor Surge and a Nocturnal Blood Pressure Decline

There is continuing controversy over whether the pattern of circadian blood pressure (BP) variation that includes a nocturnal decline in BP and a morning pressor surge has prognostic significance for stroke risk. In this study, we followed the incidence of stroke in 1430 subjects aged > or =40 years in Ohasama, Japan, for an average of 10.4 years. The association between stroke risk and the pattern of circadian BP variation was analyzed with a Cox proportional hazards model after adjustment for possible confounding factors. There was no significant association between total stroke risk and the nocturnal decline in BP (percentage decline from diurnal level) or between total stroke risk and the morning pressor surge. The cerebral infarction risk was significantly higher in subjects with a <10% nocturnal decline in BP as compared with subjects who had a > or =10% nocturnal decline in BP (P=0.04). The morning pressor surge was not associated with a risk of cerebral infarction. On the other hand, an increased risk of cerebral hemorrhage was observed in subjects with a large morning pressor surge (> or =25 mm Hg; P=0.04). Intracerebral hemorrhage was also observed more frequently in extreme dippers (those with a > or =20% nocturnal decline in BP) than dippers (those with a 10% to 19% decline; P=0.02). A disturbed nocturnal decline in BP is associated with cerebral infarction, whereas a large morning pressor surge and a large nocturnal decline in BP, which are analogous to a large diurnal increase in BP, are both associated with cerebral hemorrhage.

Efficacy and duration of action of the four selective angiotensin II subtype 1 receptor blockers, losartan, candesartan, valsartan and telmisartan, in patients with essential hypertension determined by home blood pressure measurements

Our objective was to compare the efficacy and duration of action of 4 angiotensin II receptor blockers (ARBs)--losartan (25-100 mg), candesartan (2-12 mg), valsartan (40-80 mg), and telmisartan (10-40 mg)-in patients with essential hypertension using self-measurement of blood pressure at home (home BP) and to examine the differential effect of the four ARBs on home pulse pressure (home PP). After a 2-week run-in period, each of the 4 ARBs was assigned to subjects who were diagnosed as having hypertension on the basis of home BP and who were over 30 years old. The subjects were asked to take the ARB once daily in the morning and to measure home BP once in the evening and in the morning. We compared the efficacy of each ARB on home BP and home PP and assessed the duration of the BP-lowering effect using the morning effect versus evening effect ratio (M/E ratio). The antihypertensive effects of telmisartan on home systolic BP (SBP) both in the evening and in the morning and on home diastolic BP (DBP) in the morning were significantly greater than those of losartan. The effect of each ARB on home BP in the morning and in the evening was expressed as a ratio (M/E ratio). The M/E ratios of SBP/DBP in patients treated with losartan, candesartan, valsartan, and telmisartan were 0.49/0.16, 0.69/1.01, 0.82/0.88, and 0.88/0.88, respectively. The home PP-lowering effect was greater for valsartan and telmisartan than for losartan and candesartan in the morning. Among the 4 ARBs, the duration of the BP-lowering effect of losartan did not persist throughout 24 hr. The effects of the other 3 ARBs, in particular telmisartan, persisted over 24 hr when they were administered once daily in the morning. In addition, the duration of the PP-lowering effect was similar to that of the BP-lowering effect. Such long-acting property of several ARBs is essential for the modern antihypertensive treatment, and home BP measurements are useful for determining the duration of action of antihypertensive drugs. Losartan, 25 mg a day, which is usually used as an initial dose in Japan, is apparently insufficient to obtain adequate antihypertensive effect and sufficient duration of action.

Non-symmetrical double-logistic analysis of 24-h blood pressure recordings in normotensive and hypertensive rats

OBJECTIVE

To determine the suitability of a new logistic curve fitting procedure to measure the diurnal rates of transition from the active to the asleep periods separately.

METHOD

We applied this method to 24-h telemetry recordings of systolic, mean, diastolic arterial pressure (SAP, MAP, DAP, respectively), heart rate (HR) and locomotor activity of normotensive Sprague-Dawley rats (SDR) and spontaneously hypertensive rats (SHR).

RESULTS

There was a similar pattern of higher awake and lower sleep values (16 +/- 1 mmHg SAP, 77 +/- 2 bpm HR and 40 +/- 2 units activity) in SHR. In SDR, awake-asleep differences were less for SAP (9 +/- 1 mmHg) but similar for HR (83 +/- 2 bpm). In SHR, while the blood pressure patterns were symmetrical, the rate of rise in activity and HR during arousal was more rapid than the rate of decline during the dark to light transition. By contrast in SDR, the arousal rate of increase in blood pressure and HR was much less than the rate of decline. Thus SHR have an exaggerated arousal surge in DAP compared with SDR. Double logistic provides a better fit than Cosinor or square wave and better estimates of day-night differences than partial Fourier.

CONCLUSIONS

Analysis of 24-h recordings by a new logistic curve method reveals distinct asymmetric circadian patterns of cardiovascular and activity changes in rats. The greater surge in arousal blood pressure in SHR is not associated with differences in HR or activity changes and may be inherent to the underlying mechanisms contributing to the hypertension in SHR.

Home Blood Pressure Is a Better Predictor of Carotid Atherosclerosis than Office Blood Pressure in Community-Dwelling Subjects

An increase in the thickness of the intima-media (IMT) of the carotid artery is associated with an increased risk of cardiovascular morbidity and mortality. Hypertension is one of the underlying mechanisms for the progression of carotid atherosclerosis. However, office blood pressure (BP) has been shown to have only a weak association with carotid IMT. Since self-measured home BP has less variation than office BP, home BP could be a better predictor of carotid atherosclerosis. To explore this hypothesis, we compared the relationships between carotid IMT and office BP or home BP in a community-dwelling population. One-hundred and one community residents, aged 50 years or older and not taking any medication, were enrolled in this study. Morning home BP was measured according to the guidelines of the Japanese Society of Hypertension. The results were recorded for 2 weeks and averaged. Carotid atherosclerosis was defined as IMT > or =0.80 mm, which corresponds to the first quartile. Home systolic BP showed a more significant association with carotid IMT (r=0.422, p <0.0001) than with office systolic BP (r=0.021, p=0.027). Logistic regression analysis for the presence of carotid atherosclerosis further showed that the relative risk of hypertension defined using home BP (> or =135/85 mmHg) was 6.3 (95% confidence interval [CI]: 2.0 to 19.6), while that using office BP was 1.5 (95% CI: 0.5 to 4.2). These results suggest that home BP is a better predictor of the development of carotid atherosclerosis than office BP.