Localisation of Cardiac GSαin Transgenic Mice Overexpressing GSα

The biochemical and physiological effects of GSα activation are well known; however, little is known about the anatomical localisation of GSα in the myocardium. Knowledge of the localisation might yield insights into G protein function in heart. The utility of immunocytochemistry using immunofluorescent methods is limited in normal hearts because of the low expression of GSα. In order to magnify the GSα signal, we studied transgenic mice overexpressing myocardial GSα. Immunofluorescent techniques with confocal imaging using rabbit antiserum specific for GSα were studied in frozen sections of mouse left ventricle. GSα labeling appeared to be localised to the T-tubules and intercalated disks in the GSα overexpressing mouse hearts, whereas the control mice showed background fluorescence with diffuse faint labeling. The localisation of GSα to structures involved in calcium handling and membrane conductance places GSα at a focal point in the regulation of these key functions.