AJP - Heart and Circulatory Physiology, Vol 258, Issue 6 1753-H1760, Copyright © 1990 by American Physiological Society
Duration of pressure overload alters regression of coronary circulation abnormalities
N. Ito, S. Isoyama, M. Kuroha and T. Takishima
First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Using a rat model of ascending aortic banding and debanding, we examined
how the duration of pressure overload affects reversibility in coronary
circulation abnormalities after relief of pressure overload. Four-week
banding increased left ventricular dry weight-to-body weight ratio to 158
+/- 8% of that of sham-operated controls. In isolated nonworking hearts
perfused with crystalloid solution, peak mean coronary flow rate (CFR) was
measured after brief ischemia. CFR and CFR/dry tissue weight significantly
decreased (75 +/- 5 and 54 +/- 3% of that of controls at 100 mmHg of
coronary perfusion pressure; 75 +/- 5 and 54 +/- 4% at 150 mmHg,
respectively). Four weeks after debanding was performed, CFR and CFR/dry
tissue weight increased to similar levels in controls. On the other hand,
10-wk banding produced the same degree of myocardial hypertrophy and
decreases in CFR and CFR/dry tissue weight as in 4-wk banded rats. Four
weeks after debanding was performed, CFR had not changed. CFR/dry tissue
weight increased because of regression of myocardial hypertrophy but was
significantly lower than that in rats debanded after 4 wk of banding. Thus
the duration of pressure overload does not affect the degree of coronary
circulation abnormalities in the progression process but does affect it in
the regression process.
