Expression of Proliferating Cell Nuclear Antigen in Rat Hearts Subjected to Transient Ischemia Followed by Reperfusion

Abstract

Early mechanisms involved in improving capillarity and oxygen transport to cardiac tissue exposed to transient coronary ischemia followed by reperfusion were studied in rats. Under ether anaesthesia, the left coronary artery was mechanically occluded for 3 min after which it was released, and the rats allowed to recover. After 2, 24 or 48 h the rats were sacrificed and the hearts frozen in liquid nitrogen. Frozen cross-sections were stained immunohistochemically for proliferating cell nuclear antigen (PCNA) and for the growth factors, VEGF and bFGF. No reaction for PCNA was seen in sections of sham-operated hearts but an inhomogeneous reaction occurred in annular structures in the occluded hearts at 48 h reperfusion. The stain appeared to be located in proliferating nuclei, and in the cytosol of endothelial cells. It is suggested that PCNA is stimulated by the increase in growth factors that is known to occur within 2 h after the end of the coronary occlusion. It is concluded that the increase in capillarity, indicated by the nuclear proliferation of endothelial cells, will improve the transport of oxygen to the cardiac tissues.