
growth hormone action on rat liver rna
polymerase
the effect of growth hormone on the activity of the
rna polymerase measured in this system is shown in
table 2.  it can be seen that hypophysectomy of the rat
results in decreased activity of the rna polymerase and
that the injection of 1 mg of human growth hormone into
the rat 12 h before death increased the enzyme activity
both in hypophysectomized rats and in normal rats.
however, the stimulating effect of growth hormone was
only seen in the absence of high concentrations of ammon-
ium sulphate; raising the ionic strength of the assay
medium abolished the growth hormone effect.  it should be
mentioned that addition of growth hormone in vitro in the
presence or absence of ammonium sulphate has had no
significant effect on the labelling of the rna by the
nuclear preparations.
