Experimental research on chronological changes in glomerular epithelial and endothelial cells after ischaemia

The kidney is an organ with an extremely large blood flow. During deep anesthesia or under conditions such as occur with haemorrhagic shock, however, renal blood flow falls, the blood flow being directed to other essential organs so that any fall in blood pressure throughout the whole organism is obviated. The kidney itself, however, is plunged into ischaemic conditions. The object of the present work was to study both the changes with time which occur in renal cytology after the establishment of ischaemic conditions, and to define the point in time at which renal cytology undergoes the change from a reversible to an irreversible state. In an experiment using domesticated rabbits, continuous renal artery ligation was performed (0, 1, 2.5, 5 hours) and the time course investigated histologically (mainly by observation of glomerular epithelial and endothelial cytology) with both light and electron (transmission and scanning) microscopes. The following results were obtained: 1) After one hour of ischaemia, the surface of the glomerular epithelial cells showed mild swelling and some change in its smooth appearance. One part had taken on a sponge-like appearance. 2) After 2.5 hours of ischaemia, the epithelial cells had atrophied and the entire cell surface was clearly sponge-like. It was no longer possible to distinguish the small pore-like structures that had been observed on the cell surface of normal kidney. 3) After 5 hours of ischaemia, cells were markedly atrophied and the appearance of the surface had become even more sponge-like. 4) Moreover, 2.5 hours of ischaemia was the time when, biochemically, cell metabolism had completely ceased and the permeability of the cell membrane had altered. The cell was considered to have undergone irreversible change by this stage