IS THE MITOCHONDRIAL BENZODIAZEPINE RECEPTOR INVOLVED IN THE CONTROL OF AIRWAY SMOOTH-MUSCLE TONE

1. In addition to binding to GABA(A) receptors in the central nervous system, benzodiazepines have also been reported to recognize high affi nity binding sites in several different peripheral tissues. 2. These p eripheral benzodiazepine receptors likely consist of distinct integral membrane proteins, which are predominantly localized in the outer mit ochondrial membrane and may be associated to form a heteropolymeric re ceptor complex. One such protein, identified for its ability to bind a class of benzodiazepines and isoquinolines, has been purified and the corresponding complementary DNA (cDNA) has been cloned and characteri zed. Furthermore, the structure of the rat gene encoding this protein has been clarified, thus potentially opening new insights into the mol ecular mechanisms responsible for receptor regulation.3. Although the exact physiologic and/or pharmacologic role of peripheral benzodiazepi ne receptors is still unknown, their wide tissue distribution suggests an involvement in many cellular phenomena. 4. In particular, several lines of investigation indicate that these receptors, densely expresse d on airway smooth muscle of various species, may contribute to the mo dulation of bronchomotor tone and perhaps to the pathogenesis of asthm a and airway hyperresponsiveness. (C) 1997 Elsevier Science Inc.