1. The natriuretic and
diuretic effects of
atriopeptin III (125, 250 and 500 ng kg-1, i.v.) were studied in groups of rats anaesthetized with
pentobarbitone which were either
sham controls, unilaterally nephrectomized controls,
adenine-fed or subtotal
nephrectomy chronic renal failure models. 2.
Atriopeptin III given at these doses to the
sham control animals had no effect on blood pressure, renal blood flow or glomerular filtration rate but reversibly increased urine flow, between 46% to 54%, absolute
sodium excretion, between 52% to 61%, and fractional
sodium excretion, between 48% to 54% (all P values less than 0.05) from the lowest to the highest dose. The
adenine-fed
chronic renal failure group of rats had a reduced renal blood flow of between 30 and 75%, and glomerular filtration rate of approximately 20%, compared to the
sham controls. Administration of
atriopeptin at 125, 250 and 500 ng kg-1 to the animals with
renal failure increased water and
sodium excretion to the same degree as observed in the
sham group of rats. 3. In the group of unilaterally nephrectomized rats,
atriopeptin III,
at 125, 250 and 500 ng kg-1 increased urine flow by 36%, 47% and 72%, respectively, absolute
sodium excretion by 37%, 57% and 106%, respectively, and fractional
sodium excretion by 46%, 45% and 102%, respectively. A similar pattern of responses was observed in the subtotal
nephrectomy,
chronic renal failure group in which filtration rate was approximately 4 times less than the controls. 4. These results show that in two different models of
chronic renal failure,
atriopeptin III still caused a natriuresis and diuresis. This suggests that the nephrons retain sensitivity to the
atrial natriuretic peptides in diseases such as
chronic renal failure and that these compounds may be useful in mobilizing body fluids in this situation.