Abstract
Fourteen piglets weighing 10.7 kg on the average were divided equally into two groups, a fasting and a feeding. The animals of the former group were forced to fast for 5 days, and those of the latter fed ad libitum for the same period. At the termination of the experiment, the ferrokinetics of 59Fe was determined. Although plasma volume was significantly smaller in the fasting group than the feeding group, there was no significant difference in plasma volume per kg of body weight between the two groups. There was no significant difference either in red cell mass between the groups, but red cell volume per kg of body weight was significantly greater in the fasting group. Thus, it seems likely that the plasma shift from intravascular to extravascular spaces due to weight loss resultant from fasting may have caused a decrease in plasma volume and hemoconcentration in the blood stream. A marked prolongation of plasma iron clearance and a diminution of the plasma iron turnover rate were observed in the fasting piglets. These animals had significantly less radioiron in red cells and more in the liver and spleen when examined 24 hours after intravenous injection of 59Fe. Nonheme iron concentration in the liver and spleen varied markedly from one individual to another. It was approximately half that of the growing pig. It is possible that an excess in count of red blood cells due to weight loss may cause a marked diminution in erythropoiesis, and that depressed erythropoiesis may restrict the amount of iron incorporated from the circulating iron into red cells, resulting in an increase in radioiron storage in the liver and spleen.
