Figure 1. EP₁ receptor expression and signal transduction in murine ASM cells.

(A) EP₁ gene expression was detected in cultured murine ASM cells by RT-PCR. The 501-bp product (left) corresponding to sequence from the EP₁ receptor open reading frame was only detected in reactions that included reverse transcriptase (+RT) and hybridized by Southern blots to an EP₁-specific probe (right). (B) The EP₁-selective agonist 17-PTP (1 μM) stimulated inositol phosphate (IP) production in murine ASM ~70% above basal levels (n = 4). Thrombin-stimulated inositol phosphate production was used for a positive control. *P < 0.05 versus basal. (C) Both 17-PTP and acetylcholine-stimulated [Ca²⁺]_i transients in ASM cells. Shown is a representative experiment using the doses shown in D. (D) Maximal agonist-stimulated [Ca²⁺]_i transients in ASM cells exposed to the indicated doses of agonists. Data are mean ± SEM of 5 experiments. Cch, carbachol; RFU, relative fluorescence units.