somatomedin-b and Body-Weight

Patterns of incorporation of 14C proline have been compared by whole body autoradiography to study the action of growth factors, infused for 1 week to hypophysectomized rats by subcutaneously implanted minipumps. Human growth hormone (hGH) caused dose-related increases in the width of the tibial epiphyseal cartilage and obvious weight gain, whereas only at 640 micrograms/week did Somatomedin B have a barely significant effect on these two parameters. Samples of tissues showing significant proline uptake by autoradiography were burned for direct measurement of 14C content. Both hGH (80-160 micrograms/week) and SMB (160-640 micrograms/week) significantly enhanced proline uptake in skin, tibia, liver and kidney. Whereas the Somatomedin was less active than hGH on skin it showed a greater effect on bone, significantly exceeding the apparently maximal response to hGH. The autoradiographic technique can be used not only to compare different growth factors but also to study the growth process by use of appropriate tracers.

Topics: Animals; Autoradiography; Body Weight; Cartilage; Drug Implants; Epiphyses; Growth; Growth Hormone; Hydroxyproline; Hypophysectomy; Proline; Rats; Somatomedins