Some problems of the microcirculation of the kidney.

A series of investigations was undertaken in the past years concerning the microcirculation of the kidney. Corrosion preparations with polyvinylchloride proved that in various conditions leading to shock ischaemia ensued in the kidneys which could be prevented by renal denervation. Simultaneously with the arterial ischaemia, the renal veins were normally filled. The viscosity of the polyvinylchloride solution was too great for permitting the passage through the capillaries, therefore the filling of the veins suggested the opening of arterio-venous communications. Such bypasses could be observed in the corrosion preparation with a diameter up to 50 microns. In further investigations the existence of these shunts could be proved by functional methods, too. It has been shown that following the injection of human serum albumin and in exsiccosis, the difference between the total and the capillary circulations increases. Normally this difference is only 3 to 5% of the total circulation, while in the above conditions it has been shown to increase up to 28%. Injection with Evans blue according to the method of Sellers resulted in decreased filtration and passive tubular rediffusion in shock. Experiments done concerning the countercurrent mechanism are reviewed. Finally the results of examinations based on corrosion preparations of the kidneys of patients who died of uraemia are described. In such cases gross histopathological changes have been observed involving first of all the renal vasculature; the relationship of these abnormalities with hypertension is discussed.