ABSTRACT
Like RIE‐1 cells, two of the IEC series of rat intestinal epithelial cell lines were found to express functional angiotensin receptors. As in RIE‐1 cells, treatment of IEC‐6 or IEC‐18 cells with angiotensin II (AII) activated phosphatidylinositol‐4,5‐bisphosphate (PIP~2~) hydrolysis although (in contrast to RIE‐1 cells) the magnitude of AII‐induced PIP~2~ hydrolysis was small and not associated with a mitogenic response in either IEC cell line. In terms of their other functional responses to AII (activation of protein kinase C (PKC) and a small elevation of cyclic AMP), IEC‐6 cells are otherwise similar to RIE‐1 cells whereas IEC‐18 cells exhibit some phenotypic differences to the other two cell types. Thus, whereas IEC‐6 and RIE‐1 cells each express the AT~1~ subtype of angiotensin receptor, the higher affinity receptors on IEC‐18 cells are 'atypical', being insensitive to both AT~1~‐ and AT~2~‐specific angiotensin receptor antagonists. Furthermore, in contrast to its effects in IEC‐6 and RIE‐1 cells, AII neither activates PKC nor modulates cyclic AMP levels in IEC‐18 cells. Whereas IEC‐18 cells express the myristoylated alanine‐rich C‐kinase substrate (MARCKS), immunoreactive MARCKS was not detected in IEC‐6 or RIE‐1 cells.