NOVEL SUBTYPE OF HUMAN ANGIOTENSIN-II TYPE-I RECEPTOR - ANALYSIS OF SIGNAL-TRANSDUCTION MECHANISM IN TRANSFECTED CHINESE-HAMSTER OVARY CELLS

We examined the intracellular signal transduction of two subtypes of human angiotensin II type 1 receptor (AT(1a)R and AT(1b)R) by means of the stable expression of each receptor cDNA in Chinese hamster ovary cells. Both receptors showed a rapid stimulation of phosphatidylinositol hydrolysis, a transient increase of intracellular Ca2+ concentration and an inhibitory action on the forskolin-induced cyclic AMP formation, Interestingly, at high AII concentrations (>1 mu M), these AT(1b)R-mediated responses were inhibited, whereas the AT(1a)R-mediated responses were not. Thus, the two At(1R)s are considered to be coupled to the same signal transduction cascades, but to be regulated differently on the post-translational level (presumably desensitization). (C) 1994 Academic Press, Inc.