Diurnal blood pressure variation and dietary salt in spontaneously hypertensive rats.

Calhoun, David A.; Zhu, Sutao; Wyss, J. Michael; Oparil, Suzanne

doi:10.1161/01.hyp.24.1.1

Cited by 81 publications

(61 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In rats, arterial pressure displays a marked 24-hour circadian rhythm that differs among strains and experimental treatments. 11,12,14 The present results, along with our previous study, 7 indicate that mice have a similar day-night arterial rhythm. Therefore, single daytime measurements only probe arterial pressure when it is at or near its 24-hour nadir.…”

Section: Discussionsupporting

confidence: 86%

Blood Pressure and NaCl-Sensitive Hypertension Are Influenced by Angiotensin-Converting Enzyme Gene Expression in Transgenic Mice

et al. 2002

View full text Add to dashboard Cite

Abstract-ACE plays an important role in the regulation of arterial pressure; however, a linear relationship between ACE expression and arterial pressure has not been demonstrated. The present study employed telemetric monitoring in female transgenic mice to determine the influence of partial and complete deletion of the ACE gene on basal arterial pressure and arterial pressure responses to a high-NaCl diet. On the basal NaCl diet, 24-hour mean arterial pressure was significantly correlated with the number of functional copies of the ACE gene; ie, arterial pressure was lowest in 0-copy (80Ϯ1 mm Hg), intermediate in 1-copy (100Ϯ1 mm Hg), and highest in 2-copy (113Ϯ1 mm Hg) ACE mice. The high-NaCl diet significantly increased mean arterial pressure in 0-copy (99Ϯ1 mm Hg) and 1-copy (108Ϯ1 mm Hg) mice but not in 2-copy mice (114Ϯ1 mm Hg). These results demonstrate a copy-dependent relationship between ACE gene expression and both basal arterial pressure and arterial pressure responses to a high-NaCl diet, suggesting that either partial or complete reduction in the ACE gene can alter arterial pressure. Key Words: angiotensin-converting enzyme Ⅲ arterial pressure Ⅲ renin-angiotensin system Ⅲ sodium T he ACE is a dipeptidyl carboxy-peptidase that both converts the inactive decapeptide angiotensin I to the active octapeptide angiotensin II and inactivates bradykinin by degradative metabolism. These metabolic events promote increased arterial pressure, sympathetic nervous system activity, sodium retention, and mitogenesis of vascular cells. Because of these prohypertensive effects, many pharmacological treatments for hypertension have focused on the inhibition of ACE activity.Homologous recombination techniques have been used to test the cardiovascular effects of altering expression of components of the renin-angiotensin system. Deletion of either the angiotensinogen 1,2 or angiotensin type 1 (AT 1a ) receptor 3 gene decreases arterial pressure in a copy-dependent manner, indicating a direct relationship between arterial pressure and the number of functional gene copies. In contrast, studies in ACE knockout mice have reported that although deletion of both copies of the ACE gene significantly reduces basal arterial pressure, 4,5 deletion of a single copy of the ACE gene has no effect on basal arterial pressure. 4,5 These reports suggest that arterial pressure is not influenced by partial decreases in ACE gene expression, a finding consistent with the common assumption that ACE is not rate-limiting in the renin-angiotensin system.The interpretation of these results is limited by the relatively low sensitivity of the methods that were used to record arterial pressure, ie, tail-cuff 4,6 and acute catheterization. 5

show abstract

Section: Discussionsupporting

confidence: 86%

Blood Pressure and NaCl-Sensitive Hypertension Are Influenced by Angiotensin-Converting Enzyme Gene Expression in Transgenic Mice

et al. 2002

View full text Add to dashboard Cite

show abstract

“…Clearly, this approach would confound diurnal variation and systematic trends if applied to the current study. Calhoun et al 20 also used Cosinor analysis, to examine the effects of basal and high salt diets on diurnal variation in WKY and SHR rats. However, because treatment regimens were involved, trends over the duration of the experiment were also of interest.…”

Section: Discussionmentioning

confidence: 99%

Telemetry for Cardiovascular Monitoring in a Pharmacological Study

et al. 1999

View full text Add to dashboard Cite

Abstract-Radio-telemetry systems offer the ability to measure blood pressure and heart rate in experimental models of hypertension without the stress artifacts induced by some other methods. We therefore aimed to develop improved, nonparametric regression methods for radio-telemetry data and to use these to assess the effects of pharmacological interventions on cardiac and vascular hypertrophy in the stroke-prone spontaneously hypertensive rat. One control group and 5 groups treated either with losartan (alone or in combination with N G -nitro-L-arginine methyl ester [ L-NAME]), perindopril (also alone or in combination with L-NAME), or hydralazine plus hydrochlorothiazide were monitored for 4 weeks. Cardiac hypertrophy was assessed by the left ventricle plus septum weight to body weight ratio and vascular hypertrophy by flow-cytometry analysis of vascular smooth muscle cell polyploidy. Hemodynamic series were split into trend and cyclic components by the seasonal and trend decomposition procedure based on Loess and compared between groups by Loess regression modeling. Systolic and diastolic blood pressures were reduced systematically by losartan and perindopril (PϽ10 Ϫ10) but to a lesser extent by hydralazine plus hydrochlorothiazide (PϽ10 Ϫ8 ), and diurnal variation was reduced in the latter group (PϽ10 Ϫ6). L-NAME significantly reduced the hypotensive effect only of losartan. Vascular and cardiac hypertrophy were significantly attenuated with losartan or perindopril, but were unchanged with other treatments. The new analysis proposed here identifies differential effects on trends and cyclic variation and associations with regression of end-organ damage for losartan and perindopril compared with hydralazine plus hydrochlorothiazide. The method offers a powerful tool for detailed investigation of radio-telemetry data. Key Words: telemetry Ⅲ statistics Ⅲ hypertension, genetic Ⅲ hypertrophy, cardiac Ⅲ rats M onitoring of blood pressure and heart rate in experimental models of hypertension has played an important part in the study of cardiovascular physiology, pharmacology, and more recently in the genetics of hypertension. 1Ϫ3 A wide variety of techniques have been used to obtain these measurements. Anesthesia is the simplest method but it affects normal physiological regulation and thus measurements from conscious animals are preferred. 4 The most common techniques for monitoring conscious animals use tethers or restraining devices with measurements taken via indwelling exteriorized vascular catheters or blood pressure cuffs. 5 This use of restraints and tethers introduces a significant stress artifact with well-documented elevations of plasma catecholamines and cortisol. 6 In addition, the so called noninvasive tail-cuff measurements require both warming and restraint, thus producing several stressful stimuli.Radio-telemetry provides an alternative means of obtaining blood pressure and heart rate measurements from freely moving conscious animals. It provides the ability to collect data around the clock without ...

show abstract

“…In addition to the investigation of the diurnal rhythm, 49,54,55 radiotelemetry has been used to determine the effects of locomotor activity on blood pressure. A recent study in endothelial nitric oxide synthase (eNOS) knockout mice demonstrated that the size of the activity effect (23 mm Hg in controls, 33 mm Hg in eNOS knockouts) was far greater than the day-night difference in BP, or even the effect of knocking out the eNOS gene itself.…”

Section: Advantages and Applicationsmentioning

confidence: 99%

Recommendations for Blood Pressure Measurement in Humans and Experimental Animals

Kurtz¹,

Griffin²,

Bidani³

et al. 2005

Hypertension

247

View full text Add to dashboard Cite

Abstract-In experimental animals, as in humans, techniques for measuring blood pressure (BP) have improved considerably over the past decade. In this document, we present recommendations for measuring BP in experimental animals with the goal of helping investigators select optimal methods for BP monitoring in the research laboratory. The advantages and disadvantages of various BP measurement methods are discussed and specific recommendations are provided for selecting the optimal technique depending on the study objective. Although indirect techniques that permit only sporadic measurements of BP may be suitable for some purposes, methods for directly measuring BP are generally preferred because of their ability to monitor the highly dynamic nature of BP in a comprehensive fashion. Selection of the methods to be used should ultimately be guided by the study objectives to insure that the techniques chosen are appropriate for the experimental questions being explored.

show abstract

Diurnal blood pressure variation and dietary salt in spontaneously hypertensive rats.

Cited by 81 publications

References 33 publications

Blood Pressure and NaCl-Sensitive Hypertension Are Influenced by Angiotensin-Converting Enzyme Gene Expression in Transgenic Mice

Blood Pressure and NaCl-Sensitive Hypertension Are Influenced by Angiotensin-Converting Enzyme Gene Expression in Transgenic Mice

Telemetry for Cardiovascular Monitoring in a Pharmacological Study

Recommendations for Blood Pressure Measurement in Humans and Experimental Animals

Contact Info

Product

Resources

About