Adenosine A 1 Stimulation Activates δ-Protein Kinase C in Rat Ventricular Myocytes

Abstract

By making use of immunoblotting and immunocytochemical analysis, we explored whether stimulation of adenosine A1 receptors would promote the activation of δ-protein kinase C (δ-PKC) immunolabeled with a polyclonal antibody. Immunoblot analysis of Triton X-100–soluble cell membrane and cytosolic fractions revealed the presence of a specific 75-kD band reactive to the δ-PKC polyclonal antibody. In freshly isolated rat cardiac myocytes, 28% of the total immunoreactive δ-PKC was associated with the membrane fraction, whereas 72% was associated with the soluble fraction. Under stimulation with the tumor-promoting phorbol 12-myristate 13-acetate (PMA, 500 nmol/L) used as a positive control, δ-PKC translocated to the cell membrane, with the membrane fraction representing 88% and the cytosolic fraction representing 12% of the total immunoreactive δ-PKC. Transverse optical sections performed with confocal laser microscopy showed that immunostaining with anti–δ-PKC antibody was distributed in the cytosol o...