Effects of individual and coexisting diabetes and cardiomyopathy on diastolic function in rats (Rattus norvegicus domestica)

The goal of this study was to evaluate diastolic intraventricular pressure gradients (IVPG) and 2-dimensional tissue tracking (2DTT) patterns during diabetes and cardiomyopathy. Rats (n = 60) were induced to become diabetic (DM group, n = 15) by using streptozotocin, to become cardiomyopathic (CM group, n = 15) by using isoproterenol, and to become both diabetic and cardiomyopathic (DMCM group, n = 15); control rats (CT group, n = 15) were injected with saline. Two months after induction, all rats underwent conventional echocardiography, IVPG, and 2DTT and then were euthanized for microscopic examination of cardiac fibrosis. Compared with the controls, all 3 treated groups showed diastolic dysfunction and delayed cardiac relaxation. DMCM rats showed the most pronounced cardiac abnormalities. In addition, CM and DMCM groups had showed decreased middle IVPG, whereas DMCM rats had decreased midapical IVPG. Although the overall IVPG of the CM group was normal, the middle segment was significantly decreased. 2DTT results showed that the DMCM group had a delay in relaxation compared with other groups. IVPG and 2DTT can be used to overcome the limitation of conventional echocardiographic methods and reveal diastolic dysfunction. DM worsened diastolic function during cardiac disease.