Change in Systolic Loading Sequences Produced the Different Remodeling of Hypertrophic Left Ventricle in Rats

慢性圧負荷心における左室駆出期のloading sequenceの変化と左室リモデリングの関連性に及ぼす影響

Change in Systolic Loading Sequences Produced the Different Remodeling of Hypertrophic Left Ventricle in Rats

Creators Kobayashi Shigeki

To study the effect of a change in systolic loading sequence on a development of LV hypertrophy due to pressure-overload, early systolic loading was produced by the coarctation of ascending aorta (ASC:n= 9) , and late systolic loading by the coarctation of abdominal aorta(ABD: n=8) in 6-week-old rats. Four weeks after operation, LV wt (ing)/ body wt(g) ratio increased both in ASC(2.4±0.1, p<.05) and in ABD (2.7±0.2, p<.05) compared with sham-operated group (Sham:n=9, 2.0±0.1). Peak LV pressure increased both in ASC and ABD (ASC:197±10 vs ABD:203±11mmHg, ns). We also measured LV wall thickness (W) and LV internal diameter (D) with sonomicrometry (20 MHz) , and W/D ratio was calculated as an index of eccentricity. In ASC, W/D ratio decreased compared with Sham(ASC: 0.6±0.1 vs Sham:1.1±0.2, p<.05) , indicating a development of eccentric LV hypertrophy, whereas no difference of W/D ratio was found between Sham and ABD. Collagen volume fraction (CVF: by image analyzer) in subendocardial region was higher in ABD (6.2±0.6 %) than in ASC(5.2±0.5 %, p<.05) with no significant difference in subepicardial CVF. Myocyte diameter was also larger in ABD (16.1±1.2 /μm) than in ASC(14.5±0.6 jum, p<.05). The levels of plasma angiotensin II and aldosterone at both 10 days and 4 weeks after surgery were not different among 3 groups. Our data demonstrate that different pressure-loading sequences during ventricular ejection might be an important mechanical factor for determining the type of remodeling in hypertrophic left ventricle.

[ISSN]0513-1731

[NCID]AN00243156