Failure of Newborn Rat to Respond to Hypoxia with Increased Erythropoiesis.

Publisher Website
Google Scholar
Abstract
Suckling rats, between the ages of 4 and 16 days, did not respond to hypoxia with an increased erythropoiesis as judged by increased hematocrit, hemoglobin and red cell volume. The rats used were males of the Long-Evans strain, in groups of 6, with equal numbers of controls. The hypoxic stimulus was exposure to simulated altitudes of 15,000 or of 22,000 feet, for 6 hours daily over a period of 14 days. The normal response, a polycythemia typical of the response of adult rats, was obtained in all of 4 groups of rats in which hypoxia was instituted at progressively older ages, from the 18th to the 68th day of life. The failure of the rat, in the earlier neonatal period, to respond to hypoxia with increased erythropoiesis makes it improbable that hypoxia is the direct stimulus to red cell production which leads to the high values found at birth. Termination of the hypoxia at birth could not, therefore, explain the post-natal anemia or the subsequent gradual recovery from this anemia. A pituitary fraction was recently described which stimulated erythropoiesis in the hypophysectomized, adrenalectomized and normal rat, and which is also able to prevent the development of neonatal anemia when injected into the newborn rat. Since it is known that the pituitary does not produce or release some of the known trophic hormones during the early period of life, it is not impossible that lack of production or release of the erythropoietic factor, during the neonatal period, results in the development of neonatal anemia and in the failure of the newborn rat to respond to hypoxia.

This publication has 0 references indexed in Scilit: