Transforming growth factor-beta in rat kidney during compensatory renal growth.

Transforming growth factor-beta (TGF-beta) inhibits the DNA synthesis and stimulates the alkaline phosphatase activity of cultured renal cortical tubular cells. When unilateral nephrectomy was performed, TGF-beta activity content gradually decreased in the remaining kidney. An immunohistochemical study of the remaining kidney after uninephrectomy, however, showed that the expression of TGF-beta increased by the third day after uninephrectomy in the proximal tubular cells and an autoradiographic study revealed that TGF-beta expressing tubular cells were different from proliferating cells during compensatory renal growth. These results indicate that the total renal TGF-beta content decreases after uninephrectomy, while the expression of TGF-beta in the proximal tubular cells may increase and act as a brake for compensatory renal hyperplasia.