Previous work has shown that administration of
sodium cyanate inhibits the uptake of several metabolites in
tumors under conditions in which there is generally no inhibition in normal tissues of the rat. In the present work, it was found that
cyanate treatment inhibits the distribution of 3H2O, [3H]
methoxyinulin, and [14C]
sucrose in rats with greater effects in the
tumors than the normal tissues examined.
Tumor-bearing rats received i.p.
injections of
sodium cyanate (250 mg/kg
body weight). After 60 min, the rats received s.c.
injections of 3H2O. Treatment with
cyanate decreased the radioactivity in blood and liver, but greater effects were seen in five transplanted
tumors (LK1 colon
tumor and Morris
hepatomas 5123C, 7288CTC, 7777, and 9618A2).
At 10 min after injection of 3H2O, the mean radioactivities in
tumors of
cyanate-treated rats were 11 to 23% of control values and in some
tumors were still less than in controls at 60 min after
isotope injection. Evidence was obtained that the action of
cyanate was not due to osmotic effects or loss of water from the tissues. The distribution of the extracellular markers [3H]
methoxyinulin and [14C]
sucrose was also decreased in
hepatomas in
cyanate-treated rats. The data do not exclude effects on membrane permeability but suggested that
cyanate decreased circulation in the
tumors.