Echocardiographic assessment of cardiac function in diabetic db/db and transgenic db/db-hGLUT4 mice

Control db/+ and diabetic db/db mice at 6 and 12 wk of age were subjected to echocardiography to determine whether contractile function was reduced in vivo and restored in transgenic db/db-human glucose transporter 4 (hGLUT4) mice (12 wk old) in which cardiac metabolism has been normalized. Systolic function was unchanged in 6-wk-old db/db mice, but fractional shortening and velocity of circumferential fiber shortening were reduced in 12-wk-old db/db mice (43.8+/-2.1% and 8.3+/-0.5 circs/s, respectively) relative to db/+ control mice (59.5+/-2.3% and 11.8+/-0.4 circs/s, respectively). Doppler flow measurements were unchanged in 6-wk-old db/db mice. The ratio of E and A transmitral flows was reduced from 3.56+/-0.29 in db/+ mice to 2.40+/-0.20 in 12-wk-old db/db mice, indicating diastolic dysfunction. Thus a diabetic cardiomyopathy with systolic and diastolic dysfunction was evident in 12-wk-old diabetic db/db mice. Cardiac function was normalized in transgenic db/db-hGLUT4 mice, indicating that altered cardiac metabolism can produce contractile dysfunction in diabetic db/db hearts.