Cellular origin and distribution of transforming growth factor-beta in the normal rat myocardium.

Transforming growth factor-beta (TGF-beta) is a biologically active polypeptide present in normal tissues as well as transformed cells. Two structurally related forms of this peptide are TGF-beta 1 and TGF-beta 2. Using freshly isolated cardiomyocytes and non-myocyte heart cells, and a [32P]- labelled cDNA probe to human TGF-beta 1, we demonstrated that mRNA for TGF-beta 1 could be detected only in the nonmyocyte fraction of heart cells. In the present study, the distribution of TGF-beta 1 in the heart was determined by immunofluorescence staining by use of a polyclonal antibody to porcine TGF-beta 1 in cryostat sections of rat heart. Immunofluorescence staining was intense around the blood vessels and radially diffuse in the surrounding myocardium.