
abscopal effects of whole-body
x-irradiation on compensatory hypertrophy
of the rat kidney.
the weight and dna content of normal growing (i.e., intact), and
hypertrophying (i.e., following uninephrectomy) rat kidneys were
obtained from several hundred sprague-dawley white rats.  the
effect of whole body x irradiation with 500 rad and local irradiation
to the kidney with 1000 rad, was then determined by following the
rate and degree of hypertrophy and the dna content of the kidney.
when calculated on the basis of body surface area, a constant ratio
of kidney weight and of kidney dna was found in the normal, non-
hypertrophying kidneys of 5-12 week old rats.  after 21 days of
hypertrophy these values increased approximately 50 per cent over
normal in rats 4-6 weeks old at the time of nephrectomy.  for
animals 6-14 weeks old at the time of nephrectomy the corresponding
increase was only about 20 per cent.
following uninephrectomy and x irradiation with 1000 rad to the
exteriorized remaining kidney, 4 week old rats whose bodies were
lead-shielded during irradiation showed no body weight growth
retardation, no significant difference in the dna content of the
kidney, and a small but significant decrease in weight increment
of the hypertrophying kidney after 21 days.
rats exposed to 500 rad of x rays with the kidney shielded during
irradiation, when compared with nonirradiated controls, showed body
weight growth retardation, a reduction in the dna content of the
kidney, and a reduction in the amount of kidney hypertrophy 21 days
following uninephrectomy.  a still greater inhibition of both kidney
compensatory hypertrophy and the increase in dna content of the
kidney occurred after 500 rad whole body irradiation.
food restriction in nonirradiated 4 week old rats resulting in
body weight growth retardation, elicited a marked reduction in
kidney weight and in dna content of the hypertrophying kidney 21
days after uninephrectomy.
it is concluded that the reduction in kidney hypertrophy following
whole body x irradiation with 500 rad is due in some measure to an
abscopal or indirect effect, secondary to decreased body weight.
