CAPILLARY SURFACE-AREA IS REDUCED AND TISSUE THICKNESS FROM CAPILLARIES TO MYOCYTES IS INCREASED IN THE LEFT-VENTRICLE OF STREPTOZOTOCIN-DIABETIC RATS

The left ventricles of normal and diabetic rats, fixed by vascular per fusion were examined using modern stereological techniques to quantify changes in the morphology accompanying streptozotocin-induced diabete s. The heart weight to body weight ratio increased in diabetic rats wh ilst left ventricular volume remained unchanged. Papillary muscles fro m the diabetic animals showed prolonged time to peak tension and relax ation, and altered sensitivity to adrenalin and calcium. The apparent cardiomyopathy observed when body weight loss exceeds heart weight los s in experimental diabetes was accompanied by specific pathological ch anges in the composition of the left ventricle. In the diabetic animal s the volume of extracellular components increased threefold and the v olume of capillaries fell. The surface density and total surface area of capillaries was reduced, and oxygen diffusion distance to myocyte m itochondria increased. The volume fraction of myocyte mitochondria was reduced during streptozotocin-induced diabetes.