TUNNEL CAPILLARIES IN HYPERTROPHIED MYOCARDIUM OF RATS WITH AORTOCAVAL FISTULA

Male inbred rats (Wag) with aorto-caval fistula were used as a model o f volume-overloaded heart hypertrophy. Hearts were taken after 1, 2, a nd 6 months postoperatively for immunohistochemical, histological and ultrastructural investigations. Immunohistochemical staining with some anti-extracellular matrix antibodies and ultrastructural findings all owed us to recognize intracardiocytic tunnels which were intracellular invaginations of plasmalemma surrounded by basement membrane. Inside the tunnels endothelial cells forming well-developed capillaries were entrapped. Tunnel capillary formation is discussed as an adaptive resp onse to increased cardiac work due to volume overload.