Objectives To explore the changes of contractile function of diabetic myocardium and action of cyclovirobuxin-D (CVB-D).
Methods Diabetes was induced in male SD rats, using a single injection of alloxan into tail vein. untreated age-matched animals were used as controls. The right ventricular papillary muscle was dispersing and perfusing with oxygen saluted Tyrode solution by 6th week. The systolic and diastolic change of diabetic myocardium was recorded at stimulate state.
Results At 6th week diabetic rats, Tension addition, + dT/dtmax, and-dT/dtmax were smaller in diabetic rats than control (P < 0.01), while systolic and diastolic intervals in diabetes were longer than control (P < 0.01), CVB-D (33.3∼63.3 μmol·L-1) decreased-dT/dtmax of control rats in dose-dependent manner (P< 0.05), but having no significant effect on diabetes At concentration of 63.3μmol·L-1, CVB-D prolongated 1/2 systolic intervals of diabetic rats (P < 0.01), and decreased + dT/dtmaxin of control. In addition, CVB-D 15 µmol.L-1 decreased-dT/dtmax of control rats, perfused at 10min (P < 0.05), and significantly decreased + dT/dtmax-t of control, perfused at 50 min (P < 0.05). Morever, Post-rest contractile force of the control rats was enhanced, whereas that of diabetic rats appeared no significant changes.
Conclusions Systolic and diastolic function declined in diabetic myocardium by 6th week, CVB-D decreased the contractility of myocardium both in diabetes and control to some extent.