Different therapeutic responses to treadmill exercise of heart failure due to ischemia and infarction in rats.
OBJECTIVE
The effects of exercise, a therapeutic tool in ischemic heart disease (IHD), may differ in ischemic and infarcted hearts.


RESULTS
To assess this, we created coronary stenosis (CS), which reduced coronary flow reserve (CFR), or coronary occlusion to induce myocardial infarction (MI) in rats, and subjected them to treadmill exercise for either 5 (5-min Ex) or 15 min/day (15-min Ex) for 12 weeks. Left ventricular (LV) diameters were increased and ejection fractions decreased by echocardiography, and myocardial nitric oxide (NO) activity, measured by the in vitro MVO2 method, was reduced in both CS and MI rats compared with the sham. In CS rats, myocardial wall thickening fractions were not affected at 5 min of exercise, whereas they were reduced at 15 min of exercise, suggesting exercise-induced ischemia. Despite no changes in CS severity, the 5-min Ex increased CFR, ameliorated myocardial NO activity, attenuated left ventricular (LV) dysfunction and remodeling, reduced serum brain natriuretic peptide (BNP) levels, and improved survival, whereas the 15-min Ex aggravated LV dysfunction and remodeling. In contrast, neither of the exercise protocols improved these parameters in MI rats.


CONCLUSIONS
Therapeutic responses to exercise differed in ischemic and infarcted hearts, partly via circulatory modulation downstream of the epicardial CS in relation to exercise-induced ischemia. When employing exercise for IHD, the causes of IHD, as well as the exercise protocols, need to be considered to achieve optimal effects.
Yoshinari
Kazuyuki
K
First Department of Internal Medicine, Fukushima Medical University, Hikarigaoka 1, Fukushima, 960-1295, Japan.
Yaoita
Hiroyuki
H
Maehara
Kazuhira
K
Maruyama
Yukio
Y
D000818:Animals; D023921:Coronary Stenosis; D004452:Echocardiography; D005081:Exercise Therapy; D008297:Male; D023421:Models, Animal; D009203:Myocardial Infarction / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy; D017202:Myocardial Ischemia / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D009206:Myocardium / Q000378:metabolism; D020097:Natriuretic Peptide, Brain / Q000097:blood; D009569:Nitric Oxide / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000209:etiology / Q000378:metabolism; D020257:Ventricular Remodeling
D020097:Natriuretic Peptide, Brain; D009569:Nitric Oxide