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Butlin M, Tan I, Qasem A, Avolio AP. Comparison of effects of peripheral vasculature on tonometric radial pulse and cuff-based brachial pulse waveform as used in estimation of central aortic pressures. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38083400 DOI: 10.1109/embc40787.2023.10340973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
OBJECTIVE Aortic pressure estimation requires reliable peripheral pulse waveform acquisition. The peripheral waveform can change with local vascular effects that can be independent of aortic pressure. This study quantifies the effects of peripheral vasculature changes on radial and brachial waveforms. DESIGN AND METHOD In 20 subjects (37± 15 years, 7 female), brachial volumetric displacement (cuff-based) and radial tonometry waveforms were simultaneously measured whilst a cuff around the hand on the same arm was inflated to induce transmural pressures of -60, -30, -15, 0, 15 and 30 mmHg, altering local peripheral resistance and compliance by graded arterial wall unloading. Aortic blood pressure (BP), augmentation index (AIx) and ejection duration were calculated from the measurements using a generalized transfer function. The parameters under unloaded conditions were compared to baseline measurements. RESULTS Brachial systolic and diastolic BP did not change throughout the experiment. Altering peripheral resistance and compliance did not significantly change calculated aortic BP values, although changes were nominally greater for radial (maximum +8±1 mmHg) compared to brachial (maximum +2±1 mmHg) waveforms. AIx at 0 mmHg transmural pressure (maximum arterial wall unloading) was higher when derived from radial waveforms (+24±3%, p<0.001) but not when derived from brachial waveforms. CONCLUSIONS Localized changes in peripheral resistance and compliance affect tonometer acquired radial waveforms but not volumetric displacement acquired brachial pressure waveforms, as judged by computed central aortic augmentation pressure parameters. This suggests aortic pressure estimation from the brachial cuff waveform is less sensitive to peripheral vasculature disturbances that alter the peripheral arterial pulse morphology.
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Cox J, Avolio AP, Louka K, Shirbani F, Tan I, Butlin M. Blood pressure-independent neurogenic effect on conductance and resistance vessels: a consideration for cuffless blood pressure measurement? ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:7485-7488. [PMID: 34892824 DOI: 10.1109/embc46164.2021.9629936] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Pulse transit time (PTT) and pulse arrival time (PAT) are promising measures for cuffless arterial blood pressure (BP) estimation given the intrinsic arterial stiffness-BP relationship. However, arterial stiffness (and PTT) is altered by autonomically-driven smooth muscle tension changes, potentially independent of BP. This would limit PTT or PAT as accurate BP correlates, more so in resistance vessels than conductance arteries. OBJECTIVE To quantify if there is a measurable neurogenic effect on PAT measured using photoplethysmography (PPG) (path includes resistance vessels) and radial artery tonometry (path includes only conductance vessels) during physiologically induced BP changes. METHODS PATs were measured continuously in participants (n=15, 35±15 years, 9 male) using an electrocardiogram and, simultaneously, a Finometer® PRO finger sensor, a finger PPG sensor and radial artery tonometer during seated rest, cold pressor test, cycling and isometric handgrip (IHG) exercise. ΔBP/ΔPAT was calculated for each sensor and each condition. RESULTS All interventions significantly increased BP. A significant difference was observed in ΔBP/ΔPAT between cycling and both the cold pressor test and IHG exercise (p<0.05). ΔBP/ΔPAT did not differ whether measured via PPG or tonometry. CONCLUSIONS Under the conditions tested, autonomic function does not have a BP-independent effect on PAT where the path includes resistance vessels (PPG signal), likely due to the speed of the wave and the short path length of resistance vessels. Autonomic function therefore does not limit the ability for use of PPG as a signal for potentially estimating BP without a cuff.
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Spronck B, Tan I, Reesink KD, Georgevsky D, Delhaas T, Avolio AP, Butlin M. Heart rate and blood pressure dependence of aortic distensibility in rats: comparison of measured and calculated pulse wave velocity. J Hypertens 2021; 39:117-126. [PMID: 32784350 PMCID: PMC7752216 DOI: 10.1097/hjh.0000000000002608] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 06/12/2020] [Accepted: 07/07/2020] [Indexed: 11/27/2022]
Abstract
OBJECTIVES When assessing arterial stiffness, heart rate (HR) and blood pressure (BP) are potential confounders. It appears that the HR/BP dependences of pulse wave velocity (PWV) and distensibility are different, even though both assess arterial stiffness. This study aims to compare aortic PWV as measured using pulse transit time (PWVTT) and as calculated from distensibility (PWVdist) at the same measurement site and propose a solution to the disparity in dependences of PWVTT and PWVdist. METHODS Adult anaesthetized rats (n = 24) were randomly paced at HRs 300-500 bpm, at 50 bpm steps. At each step, aortic PWVTT (two pressure-tip catheters) and PWVdist (pressure-tip catheter and ultrasound wall-tracking; abdominal aorta) were measured simultaneously while BP was varied pharmacologically. RESULTS HR dependence of PWVdist paradoxically decreased at higher levels of BP. In addition, BP dependence of PWVdist was much larger than that of PWVTT. These discrepancies are explained in that standard PWVdist uses an approximate derivative of pressure to diameter, which overestimates PWV with increasing pulse pressure (PP). In vivo, PP decreases as HR increases, potentially causing a PWVdist decrease with HR. Estimating the full pressure-diameter curve for each HR corrected for this effect by enabling calculation of the true derivative at diastolic BP. This correction yielded a PWVdist that shows HR and BP dependences similar to those of PWVTT. As expected, BP dependence of all PWV metrics was much larger than HR dependence. CONCLUSION Measured and calculated PWV have different dependences on HR and BP. These differences are, at least in part, because of approximations made in using systolic and diastolic values to calculate distensibility.
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Affiliation(s)
- Bart Spronck
- Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, New South Wales, Australia
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
- Department of Biomedical Engineering, School of Engineering & Applied Science, Yale University, New Haven, Connecticut, USA
| | - Isabella Tan
- Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Koen D. Reesink
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Dana Georgevsky
- Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Tammo Delhaas
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Alberto P. Avolio
- Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Mark Butlin
- Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, New South Wales, Australia
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Spronck B, Ferruzzi J, Bellini C, Caulk AW, Murtada SI, Humphrey JD. Aortic remodeling is modest and sex-independent in mice when hypertension is superimposed on aging. J Hypertens 2020; 38:1312-1321. [PMID: 32068640 PMCID: PMC7611466 DOI: 10.1097/hjh.0000000000002400] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVES Increased central artery stiffness associates with cardiovascular disease. Among other factors, hypertension and aging are strong contributors to central artery stiffening, yet it has been difficult to separate their effects. Herein, we study isolated and combined effects of hypertension and aging on central artery remodeling in multiple mouse models as a function of sex. METHODS We biomechanically phenotyped the aorta as a function of two different methods of inducing hypertension [infusion of angiotensin II (AngII) or combining a high salt diet with inhibition of endothelial-derived nitric oxide synthase using L-NAME] in male and female wild-type and fibulin-5 null mice, the latter of which models aspects of aortic aging. RESULTS Despite increasing blood pressure similarly, salt + L-NAME led to adaptive and maladaptive remodeling in the abdominal and thoracic aorta, respectively, whereas AngII caused luminal dilatation but little remodeling of the wall. Importantly, effects of aging were more dramatic than those resulting from induced hypertension and, consequently, superimposing hypertension on aging led to modest additional changes in luminal radius and wall thickness, though wall stress and stiffness increased mainly because of the elevated pressure. CONCLUSION Our results suggest that effects of hypertension on aortic remodeling are modest when superimposed on aging in mice, largely independent of sex. These findings are consistent with general observations in humans and in spontaneously hypertensive rats, though separated here for the first time in a rodent model characterized by a severe loss of elastic fiber integrity similar to that found in the aged human aorta.
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Affiliation(s)
- Bart Spronck
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
- Department of Biomedical Engineering, Maastricht University, Maastricht, The Netherlands
| | - Jacopo Ferruzzi
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Chiara Bellini
- Department of Bioengineering, Northeastern University, Boston, Massachusetts
| | - Alexander W Caulk
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Sae-Il Murtada
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, Connecticut, USA
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Butlin M, Tan I, Spronck B, Avolio AP. Measuring Arterial Stiffness in Animal Experimental Studies. Arterioscler Thromb Vasc Biol 2020; 40:1068-1077. [PMID: 32268787 PMCID: PMC7176337 DOI: 10.1161/atvbaha.119.313861] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The arterial wall is a composite material of elastin, collagen, and extracellular matrix with acutely modifiable material properties through the action of smooth muscle cells. Therefore, arterial stiffness is a complex parameter that changes not only with long-term remodeling of the wall constituents but also with acute contraction or relaxation of smooth muscle or with changes in the acute distending pressure to which the artery is exposed. It is not possible to test all these aspects using noninvasive or even invasive techniques in humans. Full characterization of the mechanical properties of the artery and the specific arterial factors causing changes to stiffness with disease or modified lifestyle currently require animal studies. This article summarizes the major in vivo and ex vivo techniques to measure the different aspects of arterial stiffness in animal studies.
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Affiliation(s)
- Mark Butlin
- From the Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia (M.B., I.T., A.P.A.)
| | - Isabella Tan
- From the Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia (M.B., I.T., A.P.A.)
| | - Bart Spronck
- Department of Biomedical Engineering, School of Engineering & Applied Science, Yale University, New Haven, CT (B.S.).,Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, the Netherlands (B.S.)
| | - Alberto P Avolio
- From the Department of Biomedical Sciences, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia (M.B., I.T., A.P.A.)
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Leloup AJA, Van Hove CE, De Moudt S, De Meyer GRY, De Keulenaer GW, Fransen P. Vascular smooth muscle cell contraction and relaxation in the isolated aorta: a critical regulator of large artery compliance. Physiol Rep 2019; 7:e13934. [PMID: 30810292 PMCID: PMC6391714 DOI: 10.14814/phy2.13934] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 10/30/2018] [Accepted: 11/06/2018] [Indexed: 12/12/2022] Open
Abstract
Over the past few decades, isometric contraction studies of isolated thoracic aorta segments have significantly contributed to our overall understanding of the active, contractile properties of aortic vascular smooth muscle cells (VSMCs) and their cross-talk with endothelial cells. However, the physiological role of VSMC contraction or relaxation in the healthy aorta and its contribution to the pulse-smoothening capacity of the aorta is currently unclear. Therefore, we investigated the acute effects of VSMC contraction and relaxation on the isobaric biomechanical properties of healthy mouse aorta. An in-house developed set-up was used to measure isobaric stiffness parameters of periodically stretched (10 Hz) aortic segments at an extended pressure range, while pharmacologically modulating VSMC tone and endothelial cell function. We found that the effects of α1-adrenergic stimulation with phenylephrine on the pressure-stiffness relationship varied in sensitivity, magnitude and direction, with the basal, unstimulated NO production by the endothelium playing a pivotal role. We also investigated how arterial disease affected this system by using the angiotensin-II-treated mouse. Our results show that isobaric stiffness was increased and that the aortic segments demonstrated a reduced capacity for modulating the pressure-stiffness relationship. This suggests that not only increased isobaric stiffness at normal pressure, but also a reduced capacity of the VSMCs to limit the pressure-associated increase in aortic stiffness, may contribute to the pathogenesis of this mouse model. Overall, this study provides more insight in how aortic VSMC tone affects the pressure-dependency of aortic biomechanics at different physiological and pathological conditions.
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Affiliation(s)
- Arthur J. A. Leloup
- Laboratory of PhysiopharmacologyDepartment of Pharmaceutical SciencesUniversity of AntwerpAntwerpBelgium
| | - Cor E. Van Hove
- Laboratory of PharmacologyFaculty of Medicine and Health SciencesUniversity of AntwerpAntwerpBelgium
| | - Sofie De Moudt
- Laboratory of PhysiopharmacologyDepartment of Pharmaceutical SciencesUniversity of AntwerpAntwerpBelgium
| | - Guido R. Y. De Meyer
- Laboratory of PhysiopharmacologyDepartment of Pharmaceutical SciencesUniversity of AntwerpAntwerpBelgium
| | - Gilles W. De Keulenaer
- Laboratory of PhysiopharmacologyDepartment of Pharmaceutical SciencesUniversity of AntwerpAntwerpBelgium
| | - Paul Fransen
- Laboratory of PhysiopharmacologyDepartment of Pharmaceutical SciencesUniversity of AntwerpAntwerpBelgium
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Butlin M, Shirbani F, Barin E, Tan I, Spronck B, Avolio AP. Cuffless Estimation of Blood Pressure: Importance of Variability in Blood Pressure Dependence of Arterial Stiffness Across Individuals and Measurement Sites. IEEE Trans Biomed Eng 2018; 65:2377-2383. [DOI: 10.1109/tbme.2018.2823333] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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8
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Ferruzzi J, Di Achille P, Tellides G, Humphrey JD. Combining in vivo and in vitro biomechanical data reveals key roles of perivascular tethering in central artery function. PLoS One 2018; 13:e0201379. [PMID: 30192758 PMCID: PMC6128471 DOI: 10.1371/journal.pone.0201379] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 07/14/2018] [Indexed: 12/30/2022] Open
Abstract
Considerable insight into effectors of cardiovascular function can be gleaned from controlled studies on mice, especially given the diverse models that are available. Toward this end, however, there is a need for consistent and complementary methods of in vivo and in vitro data analysis, synthesis, and interpretation. The overall objective of this study is twofold. First, we present new semi-automated methods to quantify in vivo measurements of vascular function in anesthetized mice as well as new approaches to synthesize these data with those from in vitro biaxial mechanical characterizations. Second, we contrast regional differences in biomechanical behaviors along the central vasculature by combining biaxial strains measured in vivo with data on the unloaded geometry and biaxial material properties measured in vitro. Results support the hypothesis that the healthy ascending aorta stores significant elastic energy during systole, which is available to work on the heart and blood during diastole, particularly during periods of physical exertion, and further suggest that perivascular tethering allows arteries to work at lower values of wall stress and material stiffness than often assumed. The numerous measurements of vascular function and properties provided herein can also serve as reference values for normal wild-type male and female mice, to which values for myriad genetic, surgical, and pharmacological models can be compared in future studies.
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Affiliation(s)
- Jacopo Ferruzzi
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States of America
| | - Paolo Di Achille
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States of America
| | - George Tellides
- Department of Surgery, Yale School of Medicine, New Haven, CT, United States of America
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, United States of America
| | - Jay D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States of America
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, United States of America
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Butlin M, Hathway PJ, Kouchaki Z, Peebles K, Avolio AP. A simplified method for quantifying the subject-specific relationship between blood pressure and carotid-femoral pulse wave velocity. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2015:5708-11. [PMID: 26737588 DOI: 10.1109/embc.2015.7319688] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Devices that estimate blood pressure from arterial pulse wave velocity (PWV) potentially provide continuous, ambulatory blood pressure monitoring. Accurate blood pressure estimation requires reliable quantification of the relationship between blood pressure and PWV. Regression to population normal values or, when using limb artery PWV, changing hydrostatic blood pressure within the limb provides a calibration index. Population lookup tables require accurate anthropometric correlates, assuming no individual variation. Only devices that measure PWV in the limb can use limb position changes. This study proposes a method for developing a calibration curve independent of lookup tables and useful for large artery PWV measurement, such as carotid-femoral PWV (PWVcf). PWVcf was measured in 27 normal subjects (15 female, 36±19 years) in both the supine and standing position. The change in systemic pressure was measured and hydrostatic pressure change calculated from estimated vessel path length height, measured using body surface distances. Brachial diastolic blood pressure increased for all subjects from supine to standing (supine 70±8 mmHg, standing 83±8 mmHg, p<;0.001) with an additional hydrostatic change across the carotid-femoral path length of 19±2 mmHg (p<;0.001). PWVcf also increased in all subjects (supine 5.2±1.3 m/s, standing 7.3±2.2 m/s, p<;0.001). The subject-specific calibration index (ΔDP/ΔPWVcf) varied amongst the cohort (20±8 mmHg/m/s), was correlated with age (-0.57, p=0.002) and seated aortic systolic pressure (-0.38, p=0.048) and was always greater than zero. Thus, this study describes a simple but novel method of measuring an individualized calibration index using blood pressure and PWV measurements in the supine and standing position.
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10
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Hildreth CM, Boyd R, Kouchaki Z, Butlin M, Avolio AP, Pilowsky PM, Phillips JK. Increased arterial stiffness does not respond to renal denervation in an animal model of secondary hypertension. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:258-261. [PMID: 29059859 DOI: 10.1109/embc.2017.8036811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Renal denervation is a novel device based therapy promoted to reduce high blood pressure. We examined the impact of renal denervation on systolic blood pressure, renal function, and arterial stiffness in the Lewis Polycystic Kidney disease (LPK) rodent model of kidney disease. Animals were subjected to bilateral renal denervation or sham surgeries at age 6 and 12 weeks. Systolic blood pressure was monitored by tail-cuff plethysmography and renal function by urinalysis and creatinine clearance. At age 16 weeks, beat-to-beat aortic pulse wave velocity as a functional indicator of arterial stiffness was determined. Renal denervation produced an overall reduction in blood pressure in the LPK [(denervated 164±4 vs. sham-operated 180±6 mmHg, n = 6 per group, P=0.003)] and delayed, but did not prevent, the decline in renal function. Aortic pulse wave velocity was markedly elevated in the LPK compared with Lewis and was not altered by renal denervation in the LPK however a reduction was seen in the control Lewis animals. These results support the hypothesis that renal nerves contribute to secondary hypertension in conditions such as kidney disease.
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11
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De Moudt S, Leloup A, Van Hove C, De Meyer G, Fransen P. Isometric Stretch Alters Vascular Reactivity of Mouse Aortic Segments. Front Physiol 2017; 8:157. [PMID: 28360864 PMCID: PMC5352655 DOI: 10.3389/fphys.2017.00157] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 02/28/2017] [Indexed: 02/02/2023] Open
Abstract
Most vaso-reactive studies in mouse aortic segments are performed in isometric conditions and at an optimal preload, which is the preload corresponding to a maximal contraction by non-receptor or receptor-mediated stimulation. In general, this optimal preload ranges from about 1.2 to 8.0 mN/mm, which according to Laplace's law roughly correlates with transmural pressures of 10-65 mmHg. For physiologic transmural pressures around 100 mmHg, preloads of 15.0 mN/mm should be implemented. The present study aimed to compare vascular reactivity of 2 mm mouse (C57Bl6) aortic segments preloaded at optimal (8.0 mN/mm) vs. (patho) physiological (10.0-32.5 mN/mm) preload. Voltage-dependent contractions of aortic segments, induced by increasing extracellular K+, and contractions by α1-adrenergic stimulation with phenylephrine (PE) were studied at these preloads in the absence and presence of L-NAME to inhibit basal release of NO from endothelial cells (EC). In the absence of basal NO release and with higher than optimal preload, contractions evoked by depolarization or PE were attenuated, whereas in the presence of basal release of NO PE-, but not depolarization-induced contractions were preload-independent. Phasic contractions by PE, as measured in the absence of external Ca2+, were decreased at higher than optimal preload suggestive for a lower contractile SR Ca2+ content at physiological preload. Further, in the presence of external Ca2+, contractions by Ca2+ influx via voltage-dependent Ca2+ channels were preload-independent, whereas non-selective cation channel-mediated contractions were increased. The latter contractions were very sensitive to the basal release of NO, which itself seemed to be preload-independent. Relaxation by endogenous NO (acetylcholine) of aortic segments pre-contracted with PE was preload-independent, whereas relaxation by exogenous NO (diethylamine NONOate) displayed higher sensitivity at high preload. Results indicated that stretching aortic segments to higher than optimal preload depolarizes the SMC and causes Ca2+ unloading of the contractile SR, making them extremely sensitive to small changes in the basal release of NO from EC as can occur in hypertension or arterial stiffening.
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Affiliation(s)
- Sofie De Moudt
- Laboratory of Physiopharmacology, Department of Pharmaceutical Sciences, University of Antwerp Antwerp, Belgium
| | - Arthur Leloup
- Laboratory of Physiopharmacology, Department of Pharmaceutical Sciences, University of Antwerp Antwerp, Belgium
| | - Cor Van Hove
- Laboratory of Pharmacology, Faculty of Medicine and Health Sciences, University of Antwerp Antwerp, Belgium
| | - Guido De Meyer
- Laboratory of Physiopharmacology, Department of Pharmaceutical Sciences, University of Antwerp Antwerp, Belgium
| | - Paul Fransen
- Laboratory of Physiopharmacology, Department of Pharmaceutical Sciences, University of Antwerp Antwerp, Belgium
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12
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Grillo A, Lonati LM, Guida V, Parati G. Cardio-ankle vascular stiffness index (CAVI) and 24 h blood pressure profiles. Eur Heart J Suppl 2017. [DOI: 10.1093/eurheartj/suw060] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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13
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Steppan J, Bergman Y, Viegas K, Armstrong D, Tan S, Wang H, Melucci S, Hori D, Park SY, Barreto SF, Isak A, Jandu S, Flavahan N, Butlin M, An SS, Avolio A, Berkowitz DE, Halushka MK, Santhanam L. Tissue Transglutaminase Modulates Vascular Stiffness and Function Through Crosslinking-Dependent and Crosslinking-Independent Functions. J Am Heart Assoc 2017; 6:JAHA.116.004161. [PMID: 28159817 PMCID: PMC5523743 DOI: 10.1161/jaha.116.004161] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Background The structural elements of the vascular wall, namely, extracellular matrix and smooth muscle cells (SMCs), contribute to the overall stiffness of the vessel. In this study, we examined the crosslinking‐dependent and crosslinking‐independent roles of tissue transglutaminase (TG2) in vascular function and stiffness. Methods and Results SMCs were isolated from the aortae of TG2−/− and wild‐type (WT) mice. Cell adhesion was examined by using electrical cell–substrate impedance sensing and PicoGreen assay. Cell motility was examined using a Boyden chamber assay. Cell proliferation was examined by electrical cell–substrate impedance sensing and EdU incorporation assays. Cell micromechanics were studied using magnetic torsion cytometry and spontaneous nanobead tracer motions. Aortic mechanics were examined by tensile testing. Vasoreactivity was studied by wire myography. SMCs from TG2−/− mice had delayed adhesion, reduced motility, and accelerated de‐adhesion and proliferation rates compared with those from WT. TG2−/− SMCs were stiffer and displayed fewer cytoskeletal remodeling events than WT. Collagen assembly was delayed in TG2−/− SMCs and recovered with adenoviral transduction of TG2. Aortic rings from TG2−/− mice were less stiff than those from WT; stiffness was partly recovered by incubation with guinea pig liver TG2 independent of crosslinking function. TG2−/− rings showed augmented response to phenylephrine‐mediated vasoconstriction when compared with WT. In human coronary arteries, vascular media and plaque, high abundance of fibronectin expression, and colocalization with TG2 were observed. Conclusions TG2 modulates vascular function/tone by altering SMC contractility independent of its crosslinking function and contributes to vascular stiffness by regulating SMC proliferation and matrix remodeling.
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Affiliation(s)
- Jochen Steppan
- Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University, Baltimore, MD
| | - Yehudit Bergman
- Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University, Baltimore, MD
| | - Kayla Viegas
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Dinani Armstrong
- Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University, Baltimore, MD
| | - Siqi Tan
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD
| | - Huilei Wang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
| | - Sean Melucci
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD
| | - Daijiro Hori
- Department of Surgery, Johns Hopkins University, Baltimore, MD
| | - Sung Yong Park
- Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University, Baltimore, MD.,Department of Anesthesiology, Yonsei University, Seoul, Korea
| | - Sebastian F Barreto
- Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University, Baltimore, MD
| | - Abraham Isak
- Department of Environmental Health Sciences, Johns Hopkins University, Baltimore, MD
| | - Sandeep Jandu
- Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University, Baltimore, MD
| | - Nicholas Flavahan
- Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University, Baltimore, MD
| | - Mark Butlin
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Steven S An
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD.,Department of Environmental Health Sciences, Johns Hopkins University, Baltimore, MD
| | - Alberto Avolio
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | - Dan E Berkowitz
- Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University, Baltimore, MD.,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
| | - Marc K Halushka
- Department of Pathology, Johns Hopkins University, Baltimore, MD
| | - Lakshmi Santhanam
- Department of Anesthesiology & Critical Care Medicine, Johns Hopkins University, Baltimore, MD .,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
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14
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Leloup AJA, Van Hove CE, Kurdi A, De Moudt S, Martinet W, De Meyer GRY, Schrijvers DM, De Keulenaer GW, Fransen P. A novel set-up for the ex vivo analysis of mechanical properties of mouse aortic segments stretched at physiological pressure and frequency. J Physiol 2016; 594:6105-6115. [PMID: 27256450 DOI: 10.1113/jp272623] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 05/31/2016] [Indexed: 01/20/2023] Open
Abstract
KEY POINTS Cyclic stretch is known to alter intracellular pathways involved in vessel tone regulation. We developed a novel set-up that allows straightforward characterization of the biomechanical properties of the mouse aorta while stretched at a physiological heart rate (600 beats min-1 ). Active vessel tone was shown to have surprisingly large effects on isobaric stiffness. The effect of structural vessel wall alterations was confirmed using a genetic mouse model. This set-up will contribute to a better understanding of how active vessel wall components and mechanical stimuli such as stretch frequency and amplitude regulate aortic mechanics. ABSTRACT Cyclic stretch is a major contributor to vascular function. However, isolated mouse aortas are frequently studied at low stretch frequency or even in isometric conditions. Pacing experiments in rodents and humans show that arterial compliance is stretch frequency dependent. The Rodent Oscillatory Tension Set-up to study Arterial Compliance is an in-house developed organ bath set-up that clamps aortic segments to imposed preloads at physiological rates up to 600 beats min-1 . The technique enables us to derive pressure-diameter loops and assess biomechanical properties of the segment. To validate the applicability of this set-up we aimed to confirm the effects of distension pressure and vascular smooth muscle tone on arterial stiffness. At physiological stretch frequency (10 Hz), the Peterson modulus (EP ; 293 (10) mmHg) for wild-type mouse aorta increased 22% upon a rise in pressure from 80-120 mmHg to 100-140 mmHg, while, at normal pressure, EP increased 80% upon maximal contraction of the vascular smooth muscle cells. We further validated the method using a mouse model with a mutation in the fibrillin-1 gene and an endothelial nitric oxide synthase knock-out model. Both models are known to have increased arterial stiffness, and this was confirmed using the set-up. To our knowledge, this is the first set-up that facilitates the study of biomechanical properties of mouse aortic segments at physiological stretch frequency and pressure. We believe that this set-up can contribute to a better understanding of how cyclic stretch frequency, amplitude and active vessel wall components influence arterial stiffening.
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Affiliation(s)
- Arthur J A Leloup
- University of Antwerp, Department of Pharmaceutical Sciences, Laboratory of Physiopharmacology, Campus Drie Eiken, Universiteitsplein 1, B-2610, Antwerp, Belgium.
| | - Cor E Van Hove
- University of Antwerp, Faculty of Medicine and Health Sciences, Laboratory of Pharmacology, Campus Drie Eiken, Universiteitsplein 1, B-2610, Antwerp, Belgium
| | - Ammar Kurdi
- University of Antwerp, Department of Pharmaceutical Sciences, Laboratory of Physiopharmacology, Campus Drie Eiken, Universiteitsplein 1, B-2610, Antwerp, Belgium
| | - Sofie De Moudt
- University of Antwerp, Department of Pharmaceutical Sciences, Laboratory of Physiopharmacology, Campus Drie Eiken, Universiteitsplein 1, B-2610, Antwerp, Belgium
| | - Wim Martinet
- University of Antwerp, Department of Pharmaceutical Sciences, Laboratory of Physiopharmacology, Campus Drie Eiken, Universiteitsplein 1, B-2610, Antwerp, Belgium
| | - Guido R Y De Meyer
- University of Antwerp, Department of Pharmaceutical Sciences, Laboratory of Physiopharmacology, Campus Drie Eiken, Universiteitsplein 1, B-2610, Antwerp, Belgium
| | - Dorien M Schrijvers
- University of Antwerp, Department of Pharmaceutical Sciences, Laboratory of Physiopharmacology, Campus Drie Eiken, Universiteitsplein 1, B-2610, Antwerp, Belgium
| | - Gilles W De Keulenaer
- University of Antwerp, Department of Pharmaceutical Sciences, Laboratory of Physiopharmacology, Campus Drie Eiken, Universiteitsplein 1, B-2610, Antwerp, Belgium
| | - Paul Fransen
- University of Antwerp, Department of Pharmaceutical Sciences, Laboratory of Physiopharmacology, Campus Drie Eiken, Universiteitsplein 1, B-2610, Antwerp, Belgium
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15
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Mäki-Petäjä KM, Day L, Cheriyan J, Hall FC, Östör AJK, Shenker N, Wilkinson IB. Tetrahydrobiopterin Supplementation Improves Endothelial Function But Does Not Alter Aortic Stiffness in Patients With Rheumatoid Arthritis. J Am Heart Assoc 2016; 5:e002762. [PMID: 26896473 PMCID: PMC4802470 DOI: 10.1161/jaha.115.002762] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 12/16/2015] [Indexed: 02/07/2023]
Abstract
BACKGROUND Rheumatoid arthritis is a systemic inflammatory condition associated with increased cardiovascular risk that may be due to underlying endothelial dysfunction and subsequent aortic stiffening. We hypothesized that supplementation with tetrahydrobiopterin (BH4) would recouple endothelial nitric oxide synthase and thus improve endothelial function and consequently reduce aortic stiffness. METHODS AND RESULTS We conducted 2 randomized, double-blinded, placebo-controlled crossover studies examining 2 separate regimens: an acute regimen, with a single dose of BH4 400 mg versus placebo (n=18), and a short-term regimen, composed of a 1-week treatment with BH4 400 mg once daily versus placebo (n=15). Flow-mediated dilatation and aortic pulse wave velocity were studied 4 times, before and after each treatment phase. Acute BH4 supplementation led to an improvement of flow-mediated dilatation, whereas placebo had no effect (mean±SD of effect difference 2.56±4.79%; P=0.03). Similarly, 1-week treatment with BH4 improved endothelial function, but there was no change with placebo (mean±SD of effect difference 3.50±5.05%; P=0.02). There was no change in aortic pulse wave velocity following acute or short-term BH4 supplementation or placebo (mean±SD of effect difference: acute 0.09±0.67 m/s, P=0.6; short-term 0.03±1.46 m/s, P=0.9). CONCLUSION Both acute and short-term supplementation with oral BH4 improved endothelial function but not aortic stiffness. This result suggests that BH4 supplementation may be beneficial for patients with rheumatoid arthritis by improving endothelial dysfunction and potentially reducing risk of cardiovascular disease. There appears to be no causal relationship between endothelial function and aortic stiffness, suggesting that they occur in parallel, although they may share common risk factors such as inflammation.
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Affiliation(s)
- Kaisa M Mäki-Petäjä
- Division of Experimental Medicine and Immunotherapeutics, Addenbrooke's Hospital, University of Cambridge, UK
| | - Lisa Day
- Division of Experimental Medicine and Immunotherapeutics, Addenbrooke's Hospital, University of Cambridge, UK
| | - Joseph Cheriyan
- Division of Experimental Medicine and Immunotherapeutics, Addenbrooke's Hospital, University of Cambridge, UK
| | - Frances C Hall
- Rheumatology Research Unit, Addenbrooke's Hospital, University of Cambridge, UK
| | - Andrew J K Östör
- Rheumatology Research Unit, Addenbrooke's Hospital, University of Cambridge, UK
| | - Nicholas Shenker
- Rheumatology Research Unit, Addenbrooke's Hospital, University of Cambridge, UK
| | - Ian B Wilkinson
- Division of Experimental Medicine and Immunotherapeutics, Addenbrooke's Hospital, University of Cambridge, UK
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16
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Kouchaki Z, Butlin M, Avolio AP. Hemodynamics changes with acute carotid baroreceptor field stimulation are age-dependent in normotensive rats. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:2051-4. [PMID: 26736690 DOI: 10.1109/embc.2015.7318790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Carotid baroreceptor stimulation can treat resistant hypertension with possible effects on the vasculature beyond the decrease in arterial pressure. This study aims to characterize age-dependency of vascular hemodynamics changes with unilateral field stimulation of carotid baroreceptors in normotensive rats to infer underlying hemodynamic mechanisms. Anesthetized Wistar-Kyoto rats divided into two groups (young: n=10, 13-33 weeks; old: n=6, 52-58 weeks) were instrumented to measure heart rate (HR) and mean arterial pressure (MAP), and flow in the abdominal aorta and renal artery. Measures of aortic and renal artery stiffness and resistance were calculated. Baroreceptor stimulation caused a consistent reduction in MAP, HR, pulse pressure and aortic pulse wave velocity. In young rats reduced MAP (77 ± 10 to 64 ± 13 mmHg, p<;0.001) was concomitant with reduced mean aortic (40 ± 15 to 32 ± 11 ml/min, p<;0.05) and renal flow (3.0 ± 1.6 2.2 ± 1.1 ml/min, p<;0.001). However, in old rats reduced MAP (76 ± 14 to 64 ± 10 mmHg, p<;0.05) occurred with a reduced aortic resistance (1.8 ± 0.9 to 1.6 ± 0.9 mmHg.min/ml, p<;0.05), renal artery resistance (17.4 ± 2.4 to 16.5 ± 2.3 mmHg.min/ml, p<;0.05) and mean renal flow (4.5 ± 1.2 to 4.0 ± 1.1 ml/min, p<;0.05). This was consistent with reduced characteristic impedance in older rats in both the aorta (0.17 ± 0.08 to 0.13 ± 0.08 mmHg.min/ml, p<;0.05) and renal artery (4.97 ± 1.16 to 3.97 ± 1.08 mmHg.min/ml, p<;0.05). Stimulation caused a leftward shift in renal impedance phase frequency spectrum in both age groups indicating changes in wave reflection from the renal bed. Findings show that the reduction in MAP due to carotid barostimulation is associated with different hemodynamic mechanisms that depend on age.
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