We detected the expression of inducible bradykinin (BK) B1 receptor mRNA in the rat ileum by the reverse transcriptase-polymerase chain reaction (RT-PCR) method, when the isolated ileum was suspended for at least 1 hr in an aerated Tyrode's solution at 37 degrees. The induction of this mRNA was both time- and temperature-dependent, and was followed by a contractile response to des-Arg9-BK at around 3 hr of incubation; this response increased in magnitude with time and was maximal at 6 hr. In contrast, the contraction in response to BK and the expression of B2 receptor mRNA were constant throughout this 6-hr incubation period. The contraction due to des-Arg9-BK was selectively suppressed by B1 receptor antagonists, i.e. des-Arg9[Leu8]-BK and des-Arg10-HOE140, but not by the B2 antagonists D-Arg-[Hyp3,Thi5,8,D-Phe7]-BK and HOE140. The inducible des-Arg9-BK contractile response was suppressed by continuous in vitro exposure of the ileum to cycloheximide or actinomycin D, but neither inhibitor affected the contraction induced by BK, suggesting that the B1 receptor could be induced de novo. In vitro and ex vivo treatment of the ileum with dexamethasone suppressed the induction of the contractile response to des-Arg9-BK, but had no significant effect on the expression of B1 receptor mRNA. Some protein kinase C inhibitors, i.e. H7 and calphostin C, suppressed the expression of B1 receptor mRNA and diminished the contractile response to des-Arg9-BK. These results suggest that the de novo synthesis of the B1 receptor in the ileum preparation can be up-regulated at the transcriptional level (a process in which a specific isoform of protein kinase C may be involved). Additionally, these data suggest that the contractile response to des-Arg9-BK involves a process sensitive to some post-transcriptional action of dexamethasone.