Localisation of cardiac G(S alpha) in transgenic mice overexpressing G(S alpha)

The biochemical and physiological effects of G(S alpha) activation are well known; however, little is known about the anatomical localisation of G(S alpha) 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 G(S alpha). In order to magnify the G(S alpha) signal, we studied transgenic mice overexpressing myocardial G(S alpha). Immunofluorescent techniques with confocal imaging using rabbit antiserum specific for G(S alpha) were studied in frozen sections of mouse left ventricle. G(S alpha) labeling appeared to be localised to the T-tubules and intercalated disks in the G(S alpha) overexpressing mouse hearts, whereas the control mice showed background fluorescence with diffuse faint labeling. The localisation of G(S alpha) to structures involved in calcium handling and membrane conductance places G(S alpha) at a focal point in the regulation of these key functions. (C) 1997 Academic Press Limited.