Functional changes in the irradiated rat ureter: assessment by transit-time renography

Abstract

A primary requirement in the investigation of experimentally induced urinary tract obstruction is that there must be a reliable method of assessing the functional changes induced. In previous studies of the effects of X radiation on the rat urinary tract, assessment has used the relatively gross end-point of hydronephrosis development, as detected by regular renal palpation followed up by intravenous urography (Knowles, 1985; Knowles & Trott, 1987). In order to detect early, subclinical changes and to obtain quantitative measures of radiation effects, more sensitive techniques are required. One such method which has proven successful in investigating human urinary tract obstruction is gamma camera renography. Deconvolution of the gamma camera renogram enables the estimation of radionuclide transit times through the kidney. Drawing of separate regions of interest round the pelvi-calyceal region allows separate whole kidney and parenchymal transit times to be calculated (Whitfield et al, 1978; Britton et al, 1979). Using these it is possible to obtain a measure of delay due to the obstruction and to determine whether or not nephron function is reduced. We have been assessing the use of these techniques to examine changes occurring in the rat subsequent to localized irradiation of a length of ureter. This paper presents transit time results for the unobstructed urinary tract together with a description of the changes so far observed in radiation-induced obstructing uropathy.