Basal Metabolism in Experimental Anemias

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Basal metabolic changes have been observed in various types of anemia and in different stages of the same anemia. A number of theories have been advanced to explain this phenomenon, among which may be mentioned the hematopoietic activity and the presence of immature cells in the blood. While immature erythrocytes do consume more oxygen than normal red blood cells, one can hardly expect them to appreciably influence the total metabolism since they constitute such a small fraction of the body mass. Bald-ridge and his associates seem to have shown, in their recent investigation, a reciprocal relationship between the oxygen consumption and the nitrogen balance in various blood diseases but they, too, do not doubt the part sometimes played by the circulating reticulocytes in raising the respiratory metabolism. The present study is planned to inquire into this particular question and to ascertain the behavior of the gaseous exchange in anemias produced by different methods. Young male adult albino rats of approximately the same age and weight (about 300 gm.) were used. Their normal oxygen consumption in the post-absorptive state was determined by repeated estimations according to the method of Davis and van Dyke. Anemia was produced in one group of the animals by intraperitoneal injection of phenylhydrazine hydrochloride, 10 mg. per 100 gm. of body weight. In another group the rats were bled from the tail, about 2 cc. daily. Throughout the experimental period the following data were collected by standard methods: Body weight, oxygen consumption, body temperature, red and white blood cell counts, hemoglobin content, hematocrit reading, morphology of stained blood-smear, differential count and reticulocyte count. If the animal survived through the experiment it was sacrificed and autopsied. All animals lost some weight in the course of the experiment, usually not exceeding 40 gm. The picture of the bone marrow is essentially the same in the 2 types of anemia, namely, marked hyperplasia involving both myelocytic and erythroblastic elements and nearly always some megaloblastic blood formation. In the first group only 4 animals were successfully studied, the majority succumbed too early to permit observation for a sufficiently long period. In them the phenylhydrazine produced a prompt drop of the red cell count and hemoglobin concentration. The reticulocyte count rose steadily, reached its maximum (varying between 45 and 50%) in from 5 to 8 days, and after being maintained at that level for about 2 days, declined slowly. Immediately following the injection of the drug the oxygen consumption showed a rise to from 10 to 30% above the control level but this rise only lasted for from 1 to 4 days. The peak of the reticulocyte curve lagged from 4 to 8 days behind the rise of metabolism. Leucocytosis and increase of the polymorphonuclear neutrophils accompanied the anemia.