Renal medulla perfusion. Direct observations by fine detail angiography in the dog.

Abstract

The left kidney of dogs anaesthetised with intravenous pentobarbitone was explanted to the flank, in close contact with a hand film changer loaded with industrial X-ray film. Renal angiography using Thorotrast was performed before and during bleeding to an aortic pressure of 60 mm Hg. The kidneys of normal and hypotensive animals were also clamped after Thorotrast injection, fixed, and sectioned to obtain detailed radiographs of the renal circulation arrested at various stages. Patterns of normal cortical and medullary perfusion were studied, with angiographic demonstration of at least three rates of renal blood flow, and double filling of the renal veins. In haemorrhagic hypotension, there was marked slowing of the medullary circulation, which continued in the presence of severe cortical ischaemia. The anatomical boundaries of renal perfusion compartments can be precisely delineated by these methods.