Abstract
The studies were carried out on male Wistar rats. The animals were divided into two groups: control and experimental. The hematocrit value and reticulocyte count were determined in blood samples collected from control and experimental rats. The experimental rats received subcutaneous injections of phenylhydrazine manufactured by Sigma for the duration of 3 days. On the 5th day blood samples were collected from all the control and experimental animals and determinations of hematocrit and reticulocyte count were repeated. cAMP levels were determined in bone marrow extracts by means of a radiocompetitive method. The cGMP level was determined by a radioimmunological assay. A significant elevation of cAMP level was detected in experimental rats, whereas the cGMP level changed only slightly.