Kidney distension during IV urography in normal rats and in rats with artificial unilateral renal artery stenosis

Acute changes in kidney size during IV urography were studied in normal rats and in rats with artificial unilateral renal artery stenosis. In normal rats, IV bolus injection of sodium iothalamate (400 mg I/ml), 1.5 ml/kg body weight, produced an increase in area of the renal silhouette by an average maximum of 12.7% after 60 seconds. In nine out of ten rats which developed hypertension after left sided renal artery clamping, renal distension was either small or absent on the stenosed side, while the contralateral right kidney showed normal distension during IV urography. Two out of three rats, which remained normotensive after renal arterial clamping, showed normal distension of both kidneys. These results confirm earlier observations in man that the acute changes in size of the kidney during IV urography can be used as an aid in the urographic screening of hypertensive patients for significant renal arterial stenosis. In all rats with arterial clamp and hypertension, the stenosed kidney was smaller than its contralateral mate. An index between the size of the non-stenosed and the stenosed kidneys greater than 1.15 was only seen in these particular rats.