AN EVALUATION OF THE ROLE OF POLYAMINES IN DIFFERENT MODELS OF KIDNEYHYPERTROPHY IN MICE

The role of ornithine decarboxylase (ODC) and polyamines in kidney hyp ertrophy is controversial. Since part of this controversy could be rel ated to differences in the model system used by the different authors, we studied the changes in renal ODC and polyamines in six different m odels of kidney hypertrophy in mice, including compensatory renal hype rtrophy produced by unilateral nephrectomy, experimental diabetes, pot assium depletion and treatment with hormones such as testosterone, thy roxine and fluorocortisone. Only in the case of renal hypertrophy prod uced by testosterone administration was there a significant increase i n ODC activity and putrescine content in the kidneys. However, the con comitant treatment with difluoromethylornithine (DFMO), an irreversibl e inhibitor of ODC, as a 2% solution in the drinking water completely abolished the increase of renal ODC, but the kidney weights increased and other androgenic effects, such as the induction of renal beta-gluc uronidase, were not affected. Moreover, DFMO-treatment did not prevent the kidney enlargement produced in other types of hypertrophy, even i n the cases associated with hyperplasia. The present results support t he premise that, at least in mice, the increase in ODC activity and po lyamine biosynthesis is not required for kidney growth, and also that in most cases renal enlargement is not accompanied by any increase in the polyamine content.