Morfologia e estereologia do miocárdio em ratos hipertensos. Correlação com o tempo de inibição da síntese do óxido nítrico

Pereira, Leila Maria Meirelles; Vianna, Glória Maria Moraes; Mandarim-de-Lacerda, Carlos Alberto

doi:10.1590/s0066-782x1998000600004

Cited by 13 publications

(6 citation statements)

References 24 publications

(32 reference statements)

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“…The inhibition of NO biosynthesis in rats with a high dosage of L-NAME induces high levels of AP, LVH, myocyte necrosis, vascular damage and interstitial fibrosis [2,20,29,44]. In hypertension, LVH is also associated with fibrotic changes in both the interstitial space and around intramyocardial coronary artery branches [17,18,30,45].…”

Section: Discussionmentioning

confidence: 99%

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Stereology and Immunohistochemistry of the Myocardium in Experimental Hypertension: Long-Term and Low-Dosage Administration of Inhibitor of the Nitric Oxide Synthesis

1999

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Morphological changes in the myocardium after left ventricular hypertrophy, due to chronic experimental hypertension, require an understanding of the quantitative relationship between myocyte and nonmyocyte compartments forming the structural framework of the myocardium. Hypertension was induced by long-term low-dosage inhibition of nitric oxide synthesis by N^G-nitro-L-arginine methyl ester (L-NAME) in rats. L-NAME (12 mg/kg) was given to animals in water ad libitum during 15 weeks. After this period, systolic blood pressure increased almost 50% as compared with that in the control group. Morphological changes in control and L-NAME animals were investigated with stereology and immunohistochemistry. Comparing control and L-NAME animals, the surface density of myocytes decreased 73.7% while the mean cross-sectional area increased 97.6% in L-NAME rats. The volume density of myocytes decreased 45.9% and the volume density of the interstitium increased 71.7% in L-NAME rats. No stereological difference was found in blood vessels comparing the two groups. Remodeling of the cardiac interstitium occurred with increased deposition of both fibronectin and type III collagen. Fibronectin was seen in both early and latter responses to infarction while type III collagen was seen mainly in areas of incomplete healing among myocytes and around intramyocardial branches of the coronary arteries. The long-term low-dosage administration of an inhibitor of the NO synthase such as L-NAME causes myocyte hypertrophy and early interstitial and perivascular fibrosis without important quantitative changes in microcirculation.

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Section: Discussionmentioning

confidence: 99%

“…The effects caused for this NO synthase inhibition have been studied quantitatively by stereology showing important changes such as increase of myocyte size and interstitial and perivascular fibrosis [28][29][30]. However, this condition is not comparable to human hypertension that is normally ore insidious.…”

Section: Introductionmentioning

confidence: 99%

Stereology and Immunohistochemistry of the Myocardium in Experimental Hypertension: Long-Term and Low-Dosage Administration of Inhibitor of the Nitric Oxide Synthesis

1999

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“…However, previous studies have shown an increase in the volume fraction of collagen in LVH as a result of pressure overload 12,16,[44][45][46][47] . The inhibition of NO biosynthesis using high doses of L-NAME induces a significant elevation of the blood pressure, LVH, myocyte necrosis, vascular damage, and interstitial fibrosis 2,9,14,48 . The current results with the lowdose and long-term administration of L-NAME showed that the pressure levels were not so high as those observed in other studies, but myocardial abnormalities were similar to those in the model with high-dosage and short-term administration of L-NAME 8,44 .…”

Section: Discussionmentioning

confidence: 99%

“…The effects of this kind of NOS inhibition were studied using stereology to examine the structural changes in the myocardium. Significant changes, such as an increase in the size of myocytes, and interstitial and perivascular fibrosis, were shown 8,13,14 . Left ventricular hypertrophy (LVH) is one of the most common manifestations of HBP.…”

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confidence: 99%

Myocardial repair with long-term and low-dose administration of a nitric oxide synthesis inhibitor. Myofibroblasts, type III collagen and fibronectin

Pessanha¹,

Hahn²,

Mandarim-de-Lacerda³

1999

Arq. Bras. Cardiol.

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“…However, there are few data in literature on morphometric aspects of the heart during senescent stage, although this muscle is widely studied, under qualitative point of view in mammals, especially in men, in several pathological processes [4][5][6][7][8][9][10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

Morfometria do miocárdio humano em indivíduos senis

Cardoso¹,

Toscano²,

Tashiro³

et al. 2006

Arq. Bras. Cardiol.

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M a i l i n g A d d r e s s :A n a E l i s a T o s c a n o • R u a F r e d e r i c o , 3 9 -E n c r u z i l h a d a -5 2 0 4 1 -5 4 0 -R e c i f e , P E -B r a z i l E-mail: aetoscano@ig.com. METHODSFive hearts from corpses of individuals without heart diseases, of both sexes, with age between 67 and 87 years old were used. The following parameters were assessed: myocyte unit cross section area (myoc. a o ); myocyte unit perimeter length (myoc. l o ); myocyte unit volume (myoc. v o ); myocyte volumetric density (myoc. V v ); number of myocytes per volume unit (Nmm ^3myoc.). The t-test of Student was used in statistic analysis. RESULTSThe analysis of differences (p < 0.05) among right (RV), left (LV) and septal (S) ventricular regions of human heart showed that myoc. a o values were lower in RV (1.51 ± 0.10 µm CONCLUSIONResults obtained show that there may be changes in dimensions of left ventricular wall myocyte cell during senescent stage. However, those differences are subtle and seem to mean the adjustment of tissue to functional changes that install along life.

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Morfologia e estereologia do miocárdio em ratos hipertensos. Correlação com o tempo de inibição da síntese do óxido nítrico

Abstract: Purpose -To study structural changes of the myocardium in relation to the time of nitric oxide synthesis inhibition.Methods -Four groups of 10 rats each were studied: 2 control groups and 2 groups with administration of LName (50mg/kg/day)

Cited by 13 publications

References 24 publications

Stereology and Immunohistochemistry of the Myocardium in Experimental Hypertension: Long-Term and Low-Dosage Administration of Inhibitor of the Nitric Oxide Synthesis

Stereology and Immunohistochemistry of the Myocardium in Experimental Hypertension: Long-Term and Low-Dosage Administration of Inhibitor of the Nitric Oxide Synthesis

Myocardial repair with long-term and low-dose administration of a nitric oxide synthesis inhibitor. Myofibroblasts, type III collagen and fibronectin

Morfometria do miocárdio humano em indivíduos senis

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