MODULATION OF FORSKOLIN-MEDIATED ADENYLYL-CYCLASE ACTIVATION BY CONSTITUTIVELY ACTIVE G(S)-COUPLED RECEPTORS

In transfected CHO cells constitutively active histamine H-2 receptors not only increase the basal cAMP level, but also enhance forskolin-in duced cAMP production. The increased forskolin response was inhibited by inverse H-2 agonists with potencies similar to those determined at basal levels. The modulation of the forskolin response was also observ ed after H-2 receptor expression in HEK-293 and Sf9 cells or TSH recep tor expression in COS-7 cells, The enhancement of forskolin-induced cA MP production seems to be a general characteristic of constitutively a ctive G(s)-coupled receptors and can be very useful to study inverse a gonism at wild-type receptors. (C) 1997 Federation of European Biochem ical Societies.