Long-Term Telemetric Recording of Arterial Pressure and Heart Rate in Mice Fed Basal and High NaCl Diets

Carlson, Scott H.; Wyss, J. Michael

doi:10.1161/01.hyp.35.2.e1

Cited by 101 publications

(91 citation statements)

References 12 publications

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“…The genetic background of our mice features DNA derived from 129/Ola strain (2 renin genes 28 ) and C57BL/6, a single renin gene strain that can also develop increased BP after salt loading. 24,29 Although the influence of salt in our genetic background may have obscured subtle changes in BP secondary to EC ET B KO, we still found that selective pharmacological antagonism of ET B during high-salt diet led to further increases in BP, as described previously in the rat. 9 Although there was no difference in BP between control and KOs during pharmacological ET B blockade, the absolute increase in BP just failed to reach statistical significance in EC-specific KOs (Pϭ0.06).…”

Section: Discussionsupporting

confidence: 72%

“…Under isoflurane anesthesia, a telemetry catheter was inserted into the left carotid artery and the transmitter device (Data Sciences) secured in the left flank as described previously. 24 Mice continued standard gel chow for 7 days after surgery before commencement of high (7.6% NaClϩH 2 O ad libitum), medium (2.5% NaClϩ1% saline ad libitum), or low (0.76% NaClϩH 2 O ad libitum) salt diets. A cohort of mice at the end of the study additionally received A192621 (30 mg/kg per day) in their gel.…”

Section: Telemetry Bp Recordingmentioning

confidence: 99%

“…9,11 All of the dietary and drug treatments were maintained for 7 days. Systolic and diastolic BP and heart rate were recorded as described previously 24 and analyzed using the Powerlab data acquisition system. All of the BP results represent the mean of values recorded over the final 24 hours of each dietary/drug intervention.…”

Section: Telemetry Bp Recordingmentioning

confidence: 99%

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Deletion of Endothelial Cell Endothelin B Receptors Does Not Affect Blood Pressure or Sensitivity to Salt

et al. 2006

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Abstract-Endothelin B receptors in different tissues regulate diverse physiological responses including vasoconstriction, vasodilatation, clearance of endothelin-1, and renal tubular sodium reabsorption. To examine the role of endothelial cell endothelin B receptors in these processes, we generated endothelial cell-specific endothelin B receptor knockout mice using a Cre-loxP approach. We have demonstrated loss of endothelial cell endothelin B receptor expression and function and preservation of nonendothelial endothelin B receptor-mediated responses through binding and functional assays. Ablation of endothelin B receptors exclusively from endothelial cells produces endothelial dysfunction in the absence of hypertension, with evidence of decreased endogenous release of NO and increased plasma endothelin-1. In contrast to models of total endothelin B receptor ablation, the blood pressure response to a high-salt diet is unchanged in endothelial cell-specific endothelin B receptor knockouts compared with control floxed mice. These findings suggest that the endothelial cell endothelin B receptor mediates a tonic vasodilator effect and that nonendothelial cell endothelin B receptors are important for the regulation of blood pressure. Key Words: endothelin Ⅲ mice Ⅲ endothelium Ⅲ receptors, endothelin Ⅲ vasodilation E ndothelin-1 (ET-1) was initially described as a potent vasoconstrictor and potential mediator of hypertension. 1,2 More recently, attention has focused on how ET-1 generated within the kidney may promote natriuresis and diuresis 3 and thus contribute to a lowering of blood pressure (BP). ET-1 acts through 2 types of receptors, endothelin receptor type A (ET A ) and endothelin receptor type B (ET B ). 4,5 Activation of ET A and ET B on vascular smooth muscle cells results in vasoconstriction. 6 In contrast, vascular endothelial cells (ECs) exclusively express the ET B subtype and mediate vasodilatation. 7 ET B has been proposed as the target receptor through which collecting duct (CD)-derived ET-1 regulates natriuresis and diuresis. 3,8,9 However, ET B may also influence BP through regulation of peripheral vascular tone, 6,7 renal hemodynamics, 10,11 and clearance of circulating ET-1. 12 The autocrine/paracrine nature of ET-1 signaling, the close interdependence between renal tubular function and intrarenal blood flow, and the modulation of peripheral vascular tone by ET-1 have made the precise mechanisms by which ET B on different cell types contribute to the regulation of BP and natriuresis difficult to define, although EC ET B may be central to each of these pathways. 13 We hypothesized that CD-derived ET-1 acted in a paracrine manner on medullary vasa recta EC ET B to regulate natriuresis 11,13 and that deletion of these receptors would result in salt-sensitive hypertension. We, thus, adopted a Cre-loxP approach that permitted specific ablation of EC ET B while preserving CD ET B expression to test this hypothesis. MethodsThe general approach to producing cell type-specific knockout (KO) of ET B throug...

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Section: Discussionsupporting

confidence: 72%

Section: Telemetry Bp Recordingmentioning

confidence: 99%

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Deletion of Endothelial Cell Endothelin B Receptors Does Not Affect Blood Pressure or Sensitivity to Salt

et al. 2006

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“…We elected the intra-abdominal placement of our transmitters to avoid the confounding effects of carotid catheterization in our mice. 42 The mortality of abdominal placement is higher, and the technical difficulty involved is greater. However, the amount of data we analyzed in our chronic study was substantial.…”

mentioning

confidence: 99%

Heart Rate Variability and Baroreflex Function in AT ₂ Receptor-Disrupted Mice

et al. 2002

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Abstract-We adapted telemetry and sequence analysis employed in humans to mice and measured heart rate variability and the spontaneous baroreflex sensitivity in angiotensin II type 2 (AT 2 ) receptor-deleted (AT 2 Ϫ/Ϫ) and wild-type (AT 2 ϩ/ϩ) mice with either deoxycorticosterone acetate (DOCA)-salt hypertension or N-nitro-L-arginine methylester hydrochloride (L-NAME) hypertension. Mean arterial pressure leveled during the day at 101Ϯ1 mm Hg and during the night at 109Ϯ1 mm Hg in AT 2 receptor-deleted mice, compared with 98Ϯ2 mm Hg (day) and 104Ϯ2 mm Hg (night) in wild-type mice. Mean arterial pressure increased in AT 2 receptor-deleted mice with L-NAME to 114Ϯ1 mm Hg (day) and 121Ϯ1 mm Hg (night), compared with 105Ϯ2 mm Hg (day) and 111Ϯ2 mm Hg (night), respectively. DOCA-salt also increased day and night blood pressures in AT 2 receptor-deleted mice to a greater degree than in wild-type mice. Heart rate variability in the time and frequency domain was not different between AT 2 receptor-deleted mice and AT 2 receptor-deleted mice at baseline. Systolic blood pressure variability in the low frequency band was lower in AT 2 receptor-deleted mice (0.6Ϯ0.1 ms 2 versus 3.9Ϯ1.3 ms 2 ) than in wild-type mice. Baroreceptor-heart rate reflex sensitivity was significantly increased in AT 2 receptor-deleted mice compared with wild-type mice (3.4Ϯ0.6 versus 2.1Ϯ0.5 ms/mm Hg). These differences remained after DOCA-salt and L-NAME treatments. We conclude that activation of the AT 2 receptor impairs arterial baroreceptor reflex function, probably by a central action. These data support the existence of an inhibitory central effect of the AT 2 receptor on baroreflex function. Although not yet as clearly delineated as the AT 1 receptor, the AT 2 receptor may be responsible for counterregulating the effects induced by the AT 1 receptor. 1 In accord with this view, disruption of the AT 2 receptor caused increased blood pressure in mice and increased vasopressor responses to Ang II. [1][2][3][4][5] In experimental and human hypertension, the sensitivity of the baroreceptor control of heart rate is reduced and has been associated with an overactivity of the renin-angiotensin system. 6 Endogenous Ang II affects the baroreceptor function through the AT 1 receptor 7,8 and the AT 2 receptor via central tonic inhibitory effects. 9,10 Therefore, the AT 2 receptor gene-disrupted (Ϫ/Ϫ) mouse could be a useful model for studying the involvement of the AT 2 receptor in baroreceptor function. In man, the combined computer analysis of spontaneous blood pressure and heart rate fluctuations allows the assessment of baroreflex function without invasive or provocative interventions. We adapted telemetry to AT 2 receptor Ϫ/Ϫ and wild-type (ϩ/ϩ) mice to study blood pressure and continuous spontaneous baroreflex function in the mouse. To our knowledge, this report is the first in which these clinically accepted methods are applied to mice. MethodsExperiments were performed on 8 adult male AT 2 receptor-deleted (AT 2 Ϫ/Ϫ) and 7 male wild-type (AT 2 ϩ/...

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“…In vivo myocardial contractile function was assessed in anesthetized mice (isoflurane) using echocardiography, as described previously (21). Ambulatory heart rate and blood pressure, as well as activity, were continuously assessed by radiotelemetry, as described previously (3). Radiotelemetric devices were surgically implanted in 11-wk-old wild-type and CCM mice, which were allowed to recover from this intervention for 1 wk before a 2-wk data collection period (i.e., 12-14 wk of age).…”

Section: Animalsmentioning

confidence: 99%

A sincronização noradrenérgica e o papel da insulina na modulação da síntese da melatonina pela glândula pineal de ratos.

Garcia¹

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intact animal to the cellular, subcellular, and molecular levels. It is published 12 times a year (monthly) by the American lymphatics, including experimental and theoretical studies of cardiovascular function at all levels of organization ranging from the publishes original investigations on the physiology of the heart, blood vessels, and AJP -Heart and Circulatory Physiology Virtually every mammalian cell, including cardiomyocytes, possesses an intrinsic circadian clock. The role of this transcriptionally based molecular mechanism in cardiovascular biology is poorly understood. We hypothesized that the circadian clock within the cardiomyocyte influences diurnal variations in myocardial biology. We, therefore, generated a cardiomyocyte-specific circadian clock mutant (CCM) mouse to test this hypothesis. At 12 wk of age, CCM mice exhibit normal myocardial contractile function in vivo, as assessed by echocardiography. Radiotelemetry studies reveal attenuation of heart rate diurnal variations and bradycardia in CCM mice (in the absence of conduction system abnormalities). Reduced heart rate persisted in CCM hearts perfused ex vivo in the working mode, highlighting the intrinsic nature of this phenotype. Wild-type, but not CCM, hearts exhibited a marked diurnal variation in responsiveness to an elevation in workload (80 mmHg plus 1 M epinephrine) ex vivo, with a greater increase in cardiac power and efficiency during the dark (active) phase vs. the light (inactive) phase. Moreover, myocardial oxygen consumption and fatty acid oxidation rates were increased, whereas cardiac efficiency was decreased, in CCM hearts. These observations were associated with no alterations in mitochondrial content or structure and modest mitochondrial dysfunction in CCM hearts. Gene expression microarray analysis identified 548 and 176 genes in atria and ventricles, respectively, whose normal diurnal expression patterns were altered in CCM mice. These studies suggest that the cardiomyocyte circadian clock influences myocardial contractile function, metabolism, and gene expression.

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Long-Term Telemetric Recording of Arterial Pressure and Heart Rate in Mice Fed Basal and High NaCl Diets

Cited by 101 publications

References 12 publications

Deletion of Endothelial Cell Endothelin B Receptors Does Not Affect Blood Pressure or Sensitivity to Salt

Deletion of Endothelial Cell Endothelin B Receptors Does Not Affect Blood Pressure or Sensitivity to Salt

Heart Rate Variability and Baroreflex Function in AT ₂ Receptor-Disrupted Mice

A sincronização noradrenérgica e o papel da insulina na modulação da síntese da melatonina pela glândula pineal de ratos.

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Long-Term Telemetric Recording of Arterial Pressure and Heart Rate in Mice Fed Basal and High NaCl Diets

Cited by 101 publications

References 12 publications

Deletion of Endothelial Cell Endothelin B Receptors Does Not Affect Blood Pressure or Sensitivity to Salt

Deletion of Endothelial Cell Endothelin B Receptors Does Not Affect Blood Pressure or Sensitivity to Salt

Heart Rate Variability and Baroreflex Function in AT 2 Receptor-Disrupted Mice

A sincronização noradrenérgica e o papel da insulina na modulação da síntese da melatonina pela glândula pineal de ratos.

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Heart Rate Variability and Baroreflex Function in AT ₂ Receptor-Disrupted Mice