[Immobilization stress induced changes of ventricular electric stability in damaged heart depends on the extent of free radical damage].
Following persistent immobilization stress, differences in changes of ventricular electric stability (VES) between normal (Nor) rats and rats with myocardial damage induced by doxorubicin (Dox) were studied and compared. The latencies of arrhythmias due to ivgtt aconitine (at a rate of 0.8 microgram/min) were significantly shorter in Dox rats than in Nor rats, i.e., it was easier for Dox rats to develop arrhythmias. Persistent immobilization stress caused an initial decrease followed by a subsequent increase of VES in Nor rats. However, Dox rats following a 8 h' stress show no significant changes in latency and duration of arrhythmias, in contrast with the shortening of the two indexes in rats only immobilized for 2 h, indicating that the increased VES induced by prolonged stress in Nor rats was eliminated by Dox. Both heart rate and cAMP content in myocardial tissue of Dox rats show no obvious changes in 2 h' stress, but significantly decreased in 8 h' immobilization rats. Thus, sympathetic nervous system probably doesn't seem to account for the changes of VES in Dox rats. It was found also that 2 h' stress induced a decrease in the activity of SOD and an increase of MDA content in the myocardial tissue of Dox rats, but 8 h' stress did not do any good to the rats. These data suggest that changes of VES caused by prolonged immobilization in Dox rats have a close relationship with the extent of free radicals in myocardial tissue.
Bian
J S
JS
Department of Pharmacology, Nanjing Medical University.
Wang
Y L
YL
Li
D X
DX
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology*; D009202:Cardiomyopathies / Q000139:chemically induced / Q000150:complications / Q000503:physiopathology*; D004317:Doxorubicin; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology; D007103:Immobilization; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D051381:Rats; D013315:Stress, Psychological; D013482:Superoxide Dismutase / Q000378:metabolism*
D008315:Malondialdehyde; D004317:Doxorubicin; D013482:Superoxide Dismutase