Early and Late Effects of Growth Hormone on the Rat Diaphragm

Abstract

The mechanism of growth hormone stimulation of protein synthesis in short-term and long-term incubations differs. In studies utilizing the diaphragm of the hypophysectomized rat, it is seen that in short-term incubations hormonal stimulation of amino acid entry into the cell and incorporation into protein occurs, neither of which are affected by abolition of RNA synthesis (by actinomycin). In long-term (4 hr.) incubations, no stimulation of amino acid entry is seen while protein synthesis is stimulated, and the latter stimulation is dependent upon RNA synthesis. In addition, abolition of RNA synthesis in long-term studies results in a stimulation of amino acid entry as was seen in short-term studies.