The influence of angiotensin II-induced increase in aortic wall mass on compliance in rats in vivo

Brouwers-Ceiler, Debbie L.; Nelissen-Vrancken, H. J. M. G.; Smits, J. F. M.; Mey, Jo G. R. De

doi:10.1016/s0008-6363(96)00213-1

Cited by 22 publications

(20 citation statements)

References 36 publications

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“…These results agree with the finding that arterial wall hypertrophy can be associated with opposing effects on the elastic properties of the carotid artery in patients. 13 Furthermore, previous studies showed that the increase in wall mass resulting from chronic Ang II infusion failed to alter compliance in rat aortas 14 and that differences in compliance between hypertensive and normotensive rat aortas having similar medial cross-sections could be attributed to differences in collagen cross-linking. 15 Here we identified MMP-9 as a key element in regulating vessel compliance, influencing type I and IV collagen accumulation and degradation.…”

Section: Discussionmentioning

confidence: 99%

Role of Matrix Metalloproteinases in Early Hypertensive Vascular Remodeling

Flamant

Placier²,

Dubroca³

et al. 2007

Hypertension

158

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Abstract-Hypertension is associated with vascular remodeling characterized by rearrangement of extracellular matrix proteins. To evaluate how matrix metalloproteinase (MMP)-9 contributes to the progression of hypertensive vascular disease in vivo, wild-type (wt) or MMP-9 Ϫ/Ϫ mice were treated with angiotensin II (Ang II; 1 g/kg per minute, by minipump) plus a 5% NaCl diet during 10 days. Baseline blood pressure was equivalent in wt and knockout mice, but Ang II treatment increased systolic blood pressure to a greater extent (PϽ0.05) in MMP-9 Ϫ/Ϫ mice (94Ϯ6 to 134Ϯ6 mm Hg; PϽ0.001) than in wt animals (93Ϯ4 to 114Ϯ6 mm Hg; PϽ0.01). In wt mice, Ang II treatment increased the carotid artery pressure-diameter relationship significantly, and maximal diameter reached 981Ϯ19 m (PϽ0.01 versus sham; 891Ϯ10 m). In contrast, in MMP-9 Ϫ/Ϫ mice, carotid artery compliance was actually reduced after Ang II (PϽ0.05), and maximal diameter only reached 878Ϯ13 m. Ang II treatment induced MMP-2 and increased carotid media thickness equally in both phenotypes. However, MMP-9 induction and in situ gelatinase activity were only enhanced in Ang II-treated wt mice, and vessels from these mice also produced more collagen I breakdown products than their MMP-9 Ϫ/Ϫ counterparts (PϽ0.05). Inversely, staining for collagen IV was particularly enhanced in vessels from MMP-9 Ϫ/Ϫ mice treated with Ang II. These results demonstrate the following: (1) the onset of Ang II-induced hypertension is accompanied by increased MMP-9 activity in conductance vessels; (2) absence of MMP-9 activity results in vessel stiffness and increased pulse pressure; and (3) MMP-9 activation is associated with a beneficial role early on in hypertension by preserving vessel compliance and alleviating blood pressure increase. Key Words: angiotensin Ⅲ metalloproteinases Ⅲ remodeling Ⅲ hypertension Ⅲ collagen B lood pressure is a major determinant of vessel wall structure and composition. Any change in strain will generate counteracting radial and tangential forces that drive transformations in the vessel wall to accommodate the new pressure setting and restore basal levels of tensile stress. 1 It therefore follows that a key characteristic of hypertensive conductance arteries is increased wall thickness accompanied by enhanced rigidity. In hypertensive patients, this is manifest by elevated pulse wave velocity, an independent predictor of mortality in patients with end-stage renal failure, hypertension, and diabetes, as well as in older individuals. 2 Nevertheless, using an ex vivo model of carotid artery, we have shown recently that early vascular remodeling in the hypertensive context is actually associated with increased conductance vessel distensibility rather than rigidity. 3 In fact, results from our own laboratory 3 and others 4 -8 have shown that exposing arteries or vascular cells to stretch induces the release of matrix metalloproteinases (MMPs). This perplexing observation led us to hypothesize that increased compliance may be an early compensatory mechanism allowi...

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Section: Discussionmentioning

confidence: 99%

Role of Matrix Metalloproteinases in Early Hypertensive Vascular Remodeling

Flamant

Placier²,

Dubroca³

et al. 2007

Hypertension

158

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“…Dia is the arterial diameter (27). Replacing the elastic modulus by this relation, we can obtain the BramwellHill equation (Eq.…”

Section: Discussionmentioning

confidence: 99%

Compliance and pulse wave velocity assessed by MRI detect early aortic impairment in young patients with mutation of the smooth muscle myosin heavy chain

Lalande

Kien

Walker

et al. 2008

Magnetic Resonance Imaging

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Purpose:To evaluate aortic elasticity with MRI on young asymptomatic individuals with mutation of the smooth muscle myosin heavy chain in whom aortic enlargement is not present. Materials and Methods:Aortic compliance, aortic distensibility, and pulse wave velocity (PWV) were semiautomatically measured from MRI in 8 asymptomatic subjects having a mutation of the MYH11 gene (Mϩ) and 21 nonmutated relatives (MϪ) of similar age, sex, and blood pressure characteristics.Results: Despite a similar aortic diameter in both groups, the aortic compliance and distensibility were significantly lower in Mϩ subjects compared with MϪ (0.84 Ϯ 0.33 versus 2.03 Ϯ 0.54 mm 2 /mmHg, 1.18 Ϯ 0.62 10 Ϫ3 versus 5.11 Ϯ 1.58 10 Ϫ3 mmHg Ϫ1 , respectively), and PWV was significantly higher (5.35 Ϯ 1.53 versus 3.60 Ϯ 0.64 m.s Ϫ1 ). A threshold aortic compliance value of 1.3 mm 2 /mmHg separated the two groups. The receiver operating characteristics curve analysis indicated an optimal threshold of 2.9 10 Ϫ3 mmHg Ϫ1 for aortic distensibility (sensitivity: 87.5%, specificity: 90%), and of 4.4 m.s Ϫ1 for PWV (sensitivity: 75%, specificity: 100%). Conclusion:Young asymptomatic adults with MYH11 mutation have an aortic compliance impairment which is not detectable by the sole measurement of the aortic size. Aortic compliance measurement might be part of routine examination in patients suspected of inherited aortic disease even with a normal aortic diameter.

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“…Vessel distensibility was evaluated in rings of pulmonary artery and aorta (length 3 mm) as distensibility 5 DD/DP?D, where DD is the difference of diameter before and after 1 mm of stretching, DP is the difference in pressure at the same points and D is the final diameter of the ring [17,18]. Endothelial function was assessed as the change in wall tension in response to cumulative doses of adenosine diphosphate (ADP), as previously described [13].…”

Section: Vessel Distensibility and Endothelial Functionmentioning

confidence: 99%

Effects of cigarette smoke and hypoxia on pulmonary circulation in the guinea pig

Ferrer¹,

Peinado²,

Castañeda³

et al. 2011

European Respiratory Journal

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Cigarette smoke (CS) and chronic hypoxia (CH) can produce pulmonary hypertension. Similarities and differences between both exposures and their interaction have not been explored. The aim of the present study was to investigate the effects of CS and CH, as single factors or in combination, on the pulmonary circulation in the guinea pig.51 guinea pigs were exposed to CS for 12 weeks and 32 were sham-exposed. 50% of the animals in each group were additionally exposed to CH for the final 2 weeks. We measured pulmonary artery pressure (Ppa), and the weight ratio between the right ventricle (RV) and left ventricle plus the septum. Pulmonary artery contractility in response to noradrenaline (NA), endothelium-dependent vasodilatation and distensibility were evaluated in organ bath chambers. The number of small intrapulmonary vessels showing immunoreactivity to smooth muscle (SM) a-actin and double elastic laminas was assessed microscopically.CS and CH induced similar increases of Ppa and RV hypertrophy (p,0.05 for both), effects that were further enhanced when both factors were combined. CH increased the contractility to NA (p,0.01) and reduced the distensibility (p,0.05) of pulmonary arteries. Animals exposed to CS showed an increased number of small vessels with positive immunoreactivity to SM a-actin (p,0.01) and those exposed to CH a greater proportion of vessels with double elastic laminas (p,0.05).We conclude that CH amplifies the detrimental effects of CS on the pulmonary circulation by altering the mechanical properties of pulmonary arteries and enhancing the remodelling of pulmonary arterioles.KEYWORDS: Chronic obstructive pulmonary disease, cigarette smoke, hypoxia, pulmonary hypertension, vascular remodelling P ulmonary hypertension is a common and serious complication of chronic obstructive pulmonary disease (COPD). It is considered to result from the effects of chronic hypoxaemia on pulmonary vessels. Indeed, acute and chronic exposure to hypoxia results in smooth muscle cell (SMC) and adventitial fibroblast proliferation [1]. Nevertheless, structural changes in the pulmonary arteries of COPD patients differ from those observed in subjects exposed to a hypoxic environment. Whereas subjects living at high altitudes show medial hypertrophy, COPD patients show prominent changes in the intima [2]. Intimal hypertrophy is present in nonhypoxaemic COPD patients and in smokers with normal lung function, suggesting that vascular changes may be triggered by cigarette smoke (CS) before hypoxaemia develops.Cigarette smoking is associated with endothelial dysfunction [3], increased expression of growth factors [4] and inflammatory cell infiltrate in pulmonary arteries [5]. These factors may induce SMC proliferation and increase pulmonary vascular resistance. The molecular mechanisms by which CS induces vascular changes remain unknown, but they might be related to oxidative damage [6].The effects of hypoxia on human lungs are difficult to characterise because it is usually related to the presence of primary lu...

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The influence of angiotensin II-induced increase in aortic wall mass on compliance in rats in vivo

Abstract: An increase in aortic wall mass resulting from chronic infusion of angiotensin II does not alter the dynamic compliance of the vessel under isobaric conditions.

Cited by 22 publications

References 36 publications

Role of Matrix Metalloproteinases in Early Hypertensive Vascular Remodeling

Role of Matrix Metalloproteinases in Early Hypertensive Vascular Remodeling

Compliance and pulse wave velocity assessed by MRI detect early aortic impairment in young patients with mutation of the smooth muscle myosin heavy chain

Effects of cigarette smoke and hypoxia on pulmonary circulation in the guinea pig

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