Selective nephroangiography in the dog causing renal platelet aggregation and irregular nephrographic phase.

Selective renal artery injections of large single doses of the ionic contrast medium metrizoate produced an irregular nephrographic phase, 'patchy contrast medium retention', in 14 of 16 dogs. The irregular nephrographic phase was associated with a transient accumulation of platelets and fibrinogen in the kidney and with microscopically demonstrable transient thrombi in afferent arterioles and glomerular capillary tufts. These effects were followed by tubular damage, which was demonstrated in 4 of 6 dogs examined 48 hours after injection. Formation of thrombi was not demonstrated in 6 dogs given small single doses, which produced a homogeneous nephrographic phase. It is suggested that contrast medium induced endothelial damage is a pathogenetic mechanism in the development of thrombi and patchy contrast medium retention.