Changes in composition of heart proteins in early ontogeny under normal conditions and when the utero-placental blood flow is reduced

Abstract

The heart of rabbit embryos on the 11th, 12th, 14th, 16th, and 18th days of development was studied under normal conditions and when the utero-placental blood flow was reduced. Normally the ratio weight of heart-weight of embryo is particularly high in the period of rapid development of the hemodynamic functional system embryo-placenta-uterus (12th and 14th days), but later the ratio falls. The increase in total nitrogen in the heart and changes in the relative proportions of its fractions as a result of an increase in the content of contractile proteins and proteins of the stroma, was particularly great toward the 18th day. Under pathological conditions the weight of the embryo and the weight of the heart were reduced on all days of the experiments. The ratio weight of heart-weight of embryo toward the 18th day indicated the onset of spontaneous rehabilitation as a result of a gradual improvement in the utero-placental circulation. However, the total nitrogen content in the heart in all groups investigated remained the same as in the control or it increased, possible evidence of dehydration of the heart. Changes in the fractional composition of the heart proteins pointed to profound biochemical disturbances in the organ which could be one cause of the disturbance of its functional state.