In order to determine the mode by which growth hormone causes sodium and water retention
in animals, its action was studied using isolated toad skin. Within minutes, after
adding ovine or bovine growth hormone to the medium bathing the inside of the isolated
skin, there was an increase in sodium transport and osmotic water movement across
the skin. Pretreatment of skins with growth hormone or antidiuretic hormone abolished
or reduced stimulation of sodium transport by the other hormone. Similarities between
the actions of these two hormones suggested a common mode of action. Demonstration
of significant pressor activity in the ovine and bovine growth hormone preparations
and lack of stimulation of sodium transport or osmotic water flow across isolated
toad skin by highly purified growth hormone lead us to conclude that the sodium and
water retaining actions of ovine and bovine growth hormone may be due to contamination
with neurohypophysial hormones.
Growth Hormone - Sodium Transport - Osmotic Water Flow - Toad Skin
