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Autor: Rakusan, K

31 záznamů v PubMed Filtry

Článek

Pressure overload induced in newborn rats: effects on left ventricular growth, morphology, and function

Pediatric research. 1998 Apr ; 43 (4 Pt 1) : 521-6.

Pediatr Res
ISSN 0031-3998
Zdroj

Gradual pressure overload was induced by abdominal aortic constriction in male rats on postnatal d 6 (AC6) or 2 (AC2). At the age of 8 wk, the systemic blood pressure was measured, and the contractile performance of the left ventricle (LV) was assessed after acute ligation of the ascending aorta in open chest anesthetized animals. The LV free wall was used for the determination of collagen concentration and morphometric analysis of cardiac myocytes and capillaries. Aortic constriction resulted in LV hypertrophy, which was more pronounced in AC2 (by 71%) as compared with AC6 (by 34%) groups and correlated closely with the degree of pressure overload (r = 0.88 and 0.80, respectively). The right ventricular weight was increased by 13% in the AC2 group only. Contractile performance of the LV of aortic constricted rats was significantly higher before as well as after the acute load, but the average functional reserve was unchanged in both experimental groups. Although the maximum value of the rate of pressure development increased linearly with the degree of ventricular hypertrophy in the AC6 group (r = 0.82), a negative correlation was observed in the AC2 animals (r = -0.61). The density of myocytes was decreased, and the calculated average myocyte cross-sectional area was increased in aortic constricted rats, but the coronary capillary density and myocardial concentration of collagen remained constant. Thus, in spite of the larger cardiac growth response in the younger age group, the capillary proliferation and collagen formation were proportional to the ventricular hypertrophy. Therefore, the degrees of overload and hypertrophy do not seem to be limiting factors. Pressure overload induced in newborn rats can be a useful model for the study of mechanisms that control either the growth and differentiation of myocardium soon after birth, as well as the transition from compensated to decompensated hypertrophy at later stages.

MeSH
hemodynamika MeSH
kolagen metabolismus MeSH
krevní tlak MeSH
krysa rodu Rattus MeSH
mechanický stres MeSH
myokard metabolismus MeSH
novorozená zvířata růst a vývoj fyziologie MeSH
potkani Wistar MeSH
srdce - funkce komor * MeSH
srdeční komory růst a vývoj MeSH
vazokonstrikce MeSH
zvířata MeSH
Check Tag
krysa rodu Rattus MeSH
mužské pohlaví MeSH
zvířata MeSH
Publikační typ
časopisecké články MeSH
práce podpořená grantem MeSH
Názvy látek
kolagen MeSH

Článek

Changes in calcium handling in atrophic heterotopically isotransplanted rat hearts

Basic research in cardiology. 1995 Nov-Dec ; 90 (6) : 475-81.

Basic Res Cardiol
ISSN 0300-8428
Zdroj

Atrophy of the rat heart induced by hemodynamic unloading after heterotopic transplantation is associated with impaired relaxation while systolic function remains normal when compared to the heart of the recipient animal. To identify possible underlying mechanisms for the above, we studied some aspects of membrane calcium handling using postextrasystolic potentiation of contractions in the isolated right ventricular papillary muscle and in the left ventricle of the Langendorff-perfused heart. We also compared the alterations of the unloaded heart with those of overloaded hypertrophic hearts of rats with suprarenal aortic constriction. In the atrophic heart the degree of potentiation after one extrasystole, considered to be proportional to the trans-sarcolemmal influx of Ca2+ during an action potential, was increased by 125% when compared with recipient hearts. The rate of decay of potentiation which reflects the fraction of activator Ca2+ recirculating in the cells via the sarcoplasmic reticulum, negatively correlated with the degree of potentiation, although its mean value was not significantly altered. In hypertrophic hearts the decay of potentiation was faster when compared with the hearts of sham-operated animals, indicating a decreased recirculating fraction of Ca2+ The data suggest that the relative importance of trans-sarcolemmal Ca2+ fluxes is increased both in cardiac atrophy and hypertrophy; but their quantitative role in the control of cardiac contraction might differ.