Cardiac hypertrophy alters myocardial response to ischaemia and reperfusion in vivo.
The impact of cardiac hypertrophy on myocardial biochemical and physiological responses to ischaemia-reperfusion (I-R) was investigated in vivo. Hypertrophy was produced by aortic constriction (PH) or swimming training (TH). Open-chest rat hearts in PH, TH and a sedentary control group (SC) were subjected: (1) to ischaemia, by surgical occlusion of the main descending branch of the left coronary artery for 30 min; (2) to I-R, by releasing the occluded blood vessel for 15 min; or (3) to a sham operation. Ischaemia per se had little effect on heart oxidative and antioxidant status, or lipid peroxidation. However, I-R significantly decreased glutathione (GSH) content, increased glutathione disulfide (GSSG) content, and reduced GSH/GSSG ratio in the SC hearts. These alterations were associated with decreased activities of GSH peroxidase and GSSG reductase, and an increase in lipid peroxidation. Myocardial ATP, total adenine nucleotide content and energy charge in SC were significantly decreased after ischaemia, whereas levels of purine nucleotide derivatives, particularly adenosine, were elevated. No significant alteration of GSH status of adenine nucleotide metabolism occurred after ischaemia or I-R in hypertrophied hearts. In both PH and TH, glutathione content was significantly higher than in SC, whereas activities of GSH peroxidase and GSSG reductases were lower. TH rats maintained a higher heart rate (HR), peak systolic pressure, and energy charge during I-R. These data indicate that hypertrophied but well-functioned hearts may be more resistant to I-R induced disturbances of myocardial oxidative and antioxidant functions.
Department of Kinesiology, University of Illinois, Urbana 61801.
L L
LL
Ji
R G
RG
Fu
E W
EW
Mitchell
M
M
Griffiths
T G
TG
Waldrop
H M
HM
Swartz
D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001024:Aortic Valve Stenosis / Q000503:physiopathology; D001835:Body Weight / Q000502:physiology; D006332:Cardiomegaly / Q000473:pathology / Q000503:physiopathology*; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D005978:Glutathione / Q000378:metabolism; D006321:Heart / Q000503:physiopathology*; D015227:Lipid Peroxidation / Q000502:physiology; D009124:Muscle Proteins / Q000378:metabolism; D017202:Myocardial Ischemia / Q000473:pathology / Q000503:physiopathology*; D015428:Myocardial Reperfusion Injury / Q000473:pathology / Q000503:physiopathology*; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D009929:Organ Size / Q000502:physiology; D011685:Purine Nucleotides / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D000227:Adenine Nucleotides; D000975:Antioxidants; D009124:Muscle Proteins; D011685:Purine Nucleotides; D005978:Glutathione