Schedule-induced psychological stress and molecular structures of cardiomyocytes.
To establish a psychological stress model, we characterized in rats the effects of chronic (5-6 wk) scheduled food pellet feeding (35 mg/80 s for 8 h/day). Because the scheduled intake of pellets required that rats have access to 80% of ad libitum intake, the effect of food restriction was also examined by withholding food intermittently for 24 or 48 h each, followed by 24 h free access to food. Cardiac norepinephrine concentration was significantly increased (1,076 +/- 169 vs. 693 +/- 107 ng/g, P < 0.05) in rats subjected to pellet feeding compared with pair-fed rats (same amount of pellets in one portion) or 24- or 48-h intermittently fasted rats; similarly, the epinephrine content of adrenal glands was increased (P < 0.05). Left ventricular rate of sarcoplasmic reticulum Ca2+ uptake was decreased (P < 0.05) compared with pair-fed rats, reaching values observed for 24-h fasted rats, whereas the proportion of alpha-myosin heavy chains was only slightly reduced. Thus the schedule-induced stress arising from pellet feeding exhibits features of stress models involving physical pain and appears to stimulate the adrenergic system with subsequent impairment of Ca2+ cycling that is typical of various heart diseases.
Rupp
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Institute of Physiology, University of Tübingen, Germany. Rupp@mailer.uni-marburg.de
Maisch
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Brilla
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D000818:Animals; D001835:Body Weight; D002118:Calcium / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D004435:Eating; D004837:Epinephrine / Q000378:metabolism*; D005215:Fasting; D006321:Heart / Q000502:physiology / Q000503:physiopathology*; D006352:Heart Ventricles; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013315:Stress, Psychological / Q000378:metabolism*; D013974:Thyroxine / Q000097:blood; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood
D014284:Triiodothyronine; D018995:Myosin Heavy Chains; D013974:Thyroxine; D002118:Calcium; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine