Adaptation to the cardiac necrosis-eliciting effect of stress

¹ Institut de Médecine et de Chirurgie expérimentales, Université de Montréal, Montréal, Canada

In rats sensitized with fluorocortisol (F-COL) + Na-acetate, sudden exposure to the stress of intense muscular exercise or forced restraint produces rapidly fatal, severe myocardial necroses. In rats gradually pretreated by repeated short periods of muscular exercise or restraint, even fatal exposure to the same agent produces little or no cardiac necrosis and survival is greatly prolonged. True cross-resistance to the cardiotoxic action of various stressors can be demonstrated under these circumstances, in rats sensitized by F-COL and Na-acetate: the cardiac necrosis-producing effect of muscular exercise could be prevented by pretreatment with cold, that of cold by muscular exercise, that of noradrenaline by restraint, that of restraint by noradrenaline, and that of bone fractures by muscular exercise.