Figure 1

mRNA expression levels of various muscarinic receptor subtypes in HSG and A253 cells. (a) Total RNA was extracted from HSG and A253 cells, and reverse transcriptase-PCR (RT-PCR) was used to examine the mRNA expression levels of various muscarinic receptors. HSG cells were used as a positive control. A253 cells expressed all muscarinic receptor subtypes, except type 3 (M3R). The muscarinic receptor subtype 3 (M3R) was expressed only at an extremely low level in A253 cells. (b) Quantitative analysis of band densities. The intensity of each band was measured by densitometry, and showed that the mRNA expression level for the M3R was greatly reduced in A253 cells. The vertical bars in the graphs indicate means±s.d. of mRNA levels, normalized to the amount of GAPDH mRNA, as determined using RT-PCR. Experiments were repeated three times with essentially identical results; a summarized result is shown (n=3; ***P<0.001).