Immunochemical localization of the metabotropic glutamate receptors in therat heart

The localization of the glutamate receptor outside of the central nervous s ystem is becoming more evident. These receptors have been implicated in bra in function and pathology. It can also be envisioned that they play a vital role in the physiology of other organs and systems, We recently reported t he presence of ionotropic glutamate receptors in the rat heart. These were distributed differentially in specific cardiac structures, including nerve terminals, ganglion cells, and the conducting system, In this study, we inv estigated the presence and localization of the metabotropic glutamate recep tors (mGluRs) in the rat heart by immunohistochemistry. The experimental da ta show that the mGluR 1 alpha, mGLuR 2/3, and mGluR 5 are present in the r at heart. Their preferential localization includes nerve terminals, ganglio n cells, and elements of the conducting system. The mGluR 5 was the only re ceptor located in the intercalated disks of the cardiac muscle and in the e ndothelial lining of the blood vessels. This preferential localization to t he different components of the conducting system and cardiac neural structu res suggest that they play a role in the physiology of the heart. (C) 1999 Elsevier Science Inc.