Coronary Artery Ligation and Reperfusion in Alloxan-diabetic Rabbits: Ultrastructural and Haemodynamic Changes

The effects of left circumflex coronary artery occlusion (40 min) and subsequent reperfusion (60 min) on haemodynamics and myocardial ultrastructure were investigated in control and 10-week alloxan-diabetic rabbits. Before ligation, significant ultrastructural abnormalities, including mitochondrial swelling, disruption of cristae and deposition of lipids, were observed in hearts of diabetic animals. Occlusion of the coronary artery caused further worsening of the ultrastructural changes, including increased swelling and fragmentation of mitochondria, clumping and margination of nuclear chromatin and glycogen depletion in both control and diabetic animals. Following reperfusion, the ultrastructural alterations became even more marked, as characterized by disruption of mitochondria, hypercontraction of myofibrils and the presence of numerous amorphous electron-dense bodies. Paralleling these myocardial structural changes which were more prominent in the diabetic animals was a progressive worsening of haemodynamics, an increased incidence of arrhythmias (especially ventricular fibrillation) and cardiogenic shock in diabetic animals undergoing coronary artery ligation and reperfusion. Our studies indicate that reperfusion of the ischaemic diabetic myocardium accelerates tissue damage and is more detrimental than reperfusion in control animals.