Ripening time of reticulocytes has been measured in dogs with an experimental hemorrhagic anemia and in "doubly depleted" dogs (anemia plus hypoproteinemia).
In dogs submitted to hemorrhagic anemia alone, receiving a basal protein containing diet low in iron, the ripening time is the same as in nonanemic dogs, regardless of the potency for hemoglobin synthesis of any supplementary diet.
In anemic and hypoproteinemic dogs, i.e., "doubly depleted" dogs, a close relationship exists between the rate of hemoglobin regeneration and the ripening time of reticulocytes. Feeding a basal nonprotein diet results in a block of the ripening effect; however, if a potent diet for hemoglobin regeneration is given, the ripening time becomes normal.
Measurement of the ripening time in a "doubly depleted" dog provides a gross evaluation of the potency of a diet, as it concerns hemoglobin synthesis.
The block of reticulocyte ripening in doubly depleted dogs may be lifted by addition of amino acids to the blood in vitro. Only the ten amino acids essential for growth and glycine are necessary. It appears therefore that the block in double depletion is caused essentially by the depletion of some protein factor or factors.
The significance of these experimental results is discussed, relative to the problem of in vivo and in vitro synthesis of hemoglobin.