Effects of the prostanoids on the growth of cultured aortic vascular smooth muscle cells (VSMCs) were examined using mice lacking prostanoid receptors. Proliferation of VSMCs was assessed by measuring [(3)H]-thymidine incorporation and the cell number, and their hypertrophy by [(14)C]-leucine incorporation and protein content. In VSMCs from wild-type mice, expressions of mRNAs for the EP(4) and TP were most abundant, followed by those for the IP, EP(3) and FP, when examined by competitive reverse transcriptase-PCR. Those for the EP(1), EP(2) and DP, however, could not be detected. AE1-329, an EP(4) agonist, and cicaprost, an IP agonist, inhibited platelet derived growth factor (PDGF)-induced proliferation of VSMCs from wild-type mice; these inhibitory effects disappeared completely in VSMCs from EP(4)(-/-) and IP(-/-) mice, respectively. In accordance with these effects, AE1-329 and cicaprost stimulated cAMP production in VSMCs from wild-type mice, which were absent in VSMCs from EP(4)(-/-) and IP(-/-) mice, respectively. Effects of PGE(2) on cell proliferation and adenylate cyclase were almost similar with those of AE1-329 in VSMCs from wild-type mice, which disappeared in VSMCs from EP(4)(-/-) mice. PGD(2) inhibited PDGF-induced proliferation of VSMCs from both wild-type and DP(-/-) mice to a similar extent. This action of PGD(2) was also observed in VSMCs from EP4(-/-) and IP(-/-) mice. In VSMCs from wild-type mice, I-BOP, a TP agonist, showed potentiation of PDGF-induced hypertrophy. I-BOP failed to show this action in VSMCs from TP(-/-) mice. The specific agonists for the EP(1), EP(2) or EP(3), and PGF(2)alpha showed little effect on the growth of VSMCs. These results show that PGE(2), PGI(2) and TXA(2) modulate PDGF-induced proliferation or hypertrophy of VSMCs via the EP(4), IP and TP, respectively, and that the inhibitory effect of PGD(2) on PDGF-induced proliferation is not mediated by the DP, EP(4) or IP.