RESUMO
Nine lead electrocardiograms of non-infarcted (N = 61) and infarcted (N = 71) female Wistar rats (200-250 g) were analyzed in order to distinguish left ventricle myocardial infarction (MI) larger than 40% (LMI) from MI smaller than 40% (SMI). MI larger than 40% clearly caused a deviation of AQRS and AT from normal values of 270-360 degrees to 90-270 degrees. Infarcted rats showed Q wave in D1 larger than 1 mm with 94% sensitivity and 100% specificity. The sum of QRS positivity in V1, V2 and V6 lower than 10 mm identified MI with 82% sensitivity and 100% specificity. The data showed that MI can be easily and reliably diagnosed by electrocardiogram in the rat. However, contradicting what is frequently believed, when specificity and sensitivity were analyzed focusing on MI size, none of these current electrocardiographic indices of MI size adequately discriminates LMI from SMI.
Assuntos
Eletrocardiografia/métodos , Infarto do Miocárdio/diagnóstico , Animais , Modelos Animais de Doenças , Feminino , Infarto do Miocárdio/patologia , Ratos , Ratos Wistar , Sensibilidade e Especificidade , Índice de Gravidade de DoençaRESUMO
Nine lead electrocardiograms of non-infarcted (N = 61) and infarcted (N = 71) female Wistar rats (200-250 g) were analyzed in order to distinguish left ventricle myocardial infarction (MI) larger than 40 percent (LMI) from MI smaller than 40 percent (SMI). MI larger than 40 percent clearly caused a deviation of AQRS and AT from normal values of 270-360 degrees to 90-270 degrees. Infarcted rats showed Q wave in D1 larger than 1 mm with 94 percent sensitivity and 100 percent specificity. The sum of QRS positivity in V1, V2 and V6 lower than 10 mm identified MI with 82 percent sensitivity and 100 percent specificity. The data showed that MI can be easily and reliably diagnosed by electrocardiogram in the rat. However, contradicting what is frequently believed, when specificity and sensitivity were analyzed focusing on MI size, none of these current electrocardiographic indices of MI size adequately discriminates LMI from SMI.
Assuntos
Animais , Feminino , Ratos , Eletrocardiografia/métodos , Infarto do Miocárdio/diagnóstico , Modelos Animais de Doenças , Infarto do Miocárdio/patologia , Ratos Wistar , Sensibilidade e Especificidade , Índice de Gravidade de DoençaRESUMO
The influence of coenzyme Q10 (CoQ10) in cold stress test (-15 degrees C for 4 hours) cardiac functional impairment was studied in isolated isovolumic heart of control rats (C; n=12) and of placebo (P; n=11) and treated rats (CoQ10; n=10). In addition, electron microscopic evaluation of left ventricular (LV) slices (n=3 in each group) allowed us to analyze the myocardial ultrastructure. Maximal values of developed pressure (DPmax) were similarly decreased in cold stressed animals (C=129+/-3.9 mmHg; P=106+/-6.7 mmHg; CoQ10=91+/-3.9 mmHg); however, volume-induced enhancement of pressure generation (slope of DP volume relations: C=0.248+/-0.0203 mmHg / microl; P=0.2831+/-0.0187 mmHg / microl; CoQ10=0.2387 ( 0.0225 mmHg / microl; p > 0.05), and the duration of systole (C=80+/-1.6 ms; P=78+/-1.3 ms; CoQ10=80+/-2.7 ms) were not altered. Myocardial relaxation, evaluated by the relaxation constant (C=39+/-1.9 ms; P=42+/-3.4 ms; CoQ10=51+/-6.0 ms), as well as resting stress / strain relations were unaffected by cold stress. Myocardial samples showed that pretreatment with CoQ10 attenuates myofibrillar and mitochondrial lesions, and prevents mitochondrial fractional area increase (P: 53.11%>CoQ10: 38.78%=C: 33.87%; p< 0.005) indicating that the exogenous administration of CoQ10 can reduce cold stress myocardial injury.