EN
Gorąca, A. and Traczyk, W. Z.: Appearance of a cardiodepressant factor in the medium incubating in situ the posterior pituitary lohe of the rat. II. Differentiation from other active compounds. Acta physiol, pol., 1988, 39 (2): 98-111. In the previous article the occurrence of cardiodepressant activity in the fluid incubating in situ the posterior pituitary lobe of the rat was described (Acta Physiol. Pol., 1984, 35, 460-468). In the present study the cardiodepressant fraction of the medium incubating in situ the posterior pituitary lobe was subjected to further purification by means of thin-layer chromatography on Silica gel G. Three fractions were isolated, one of which caused a 69% decrease of beating rate of an isolated auricles of the right atrium in the two-day-old rats. In this fraction the presence of neither lipids nor compounds containing phosphate residue was detected. On the basis of the site of elution of the cardiodepressant fraction from the column filled with Sephadex G-15, it was demonstrated that the molecular weight of the cardiodepressant factor was less than 1500 and more than 832. The obtained results show that the cardiodepressant activity is associated with a low-molecule compound, probably with peptide structure, which is released into the fluid incubating in situ the posterior pituitary lobe.